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Study Unit
Gun Sights
iii
In this study unit, we’ll explain the design,
function, and installation of metallic and
optical gun sights. Following a brief history
of gun sights, we’ll address metallic rifle
sights, shotgun beads, and pistol sights.
We’ll present gun sight installation procedures and identify
the tools the job requires.
Next, you’ll learn about the development of and uses for
optical sights (scopes) for rifles, slug shotguns, and pistols.
Then, just as for metallics, we’ll detail installation
procedures.
In the final sections, we’ll address bore and final sighting,
drill and tap procedures, bolt alterations, and safety
replacement.
When you complete this study unit, you’ll be able to • Summarize the history of gun sights, identifying hallmark
developments in their evolution
• Explain the design, function, and installation of metallic andoptical sights
• Explain how to bore sight
• Explain how to sight-in rifles and pistols
• Identify correct drill and tap procedures
• Describe the process of bolt alteration
• Describe how replacing safeties often facilitates scopemounting
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METALLIC RIFLE SIGHTS: A LINE OF ACCURACY 1
Metallic Sight Development 2Metallic Sights for Modern Rifles 6Installing Metallic Rifle Sights 13Installing Dovetail-mounted Open Sights 16Zeroing and Adjusting Metallic Rifle Sights 20
HANDGUN SIGHTS: PRECISE ALIGNMENT 24
Fixed Sights 24The Paine Sight 25The Patridge Sight 26Adjustable Sights 27Dots, Outlines, and Inserts 28Glow-in-the-dark Sight 28Ribs 29Installing Handgun Sights 29Shotgun Beads 34Installing Beads 37
SCOPES: A BETTER LOOK 40
History and Development 40Functions and Features of Rifle Scopes 45Pistol, Shotgun, and Air Gun Scopes 53Reticles 58Mounting a New Scope 59Scope Installation 65Attaching the Mount 66
DRILLING AND TAPPING 69
Drill and Tap Procedures 71Attaching the Rings 78Positioning the Scope 79
SIGHTING-IN 83
Bore Sighting 84Final Sighting 87Bolt Handle Alteration for Scope Mounting 90Procedure 91Safety Replacement for Scope Mounting 93Installation Procedures 94
SELF-CHECK ANSWERS 97
EXAMINATION 101
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1
METALLIC RIFLE SIGHTS: A LINEOF ACCURACY
History doesn’t record who invented the gun sight, and we
generally believe that shooters seldom used sights over the
two or three centuries following the first shots down range.
Accordingly, the ancient matchlocks, harquebuses, and
wheel-locks couldn’t have been very accurate. The shooter
simply pointed the barrel rather than aiming, and, if the
target was close enough, the shooter may-or may not-have
hit the target.
Even so, while gun sights were exceedingly rare, evidence
exists of their use. In The Book of Rifles (Stackpole Books,
Harrisburg, Pennsylvania, 1960) author W. H. B. Smith
reports that medieval German manuscripts document the
use of front and rear sights by target shooters to ranges as
long as 200 meters as early as 1500. You can see examples
of such early sights on museum relics and in archival draw-
ings. These sights were finely crafted works with minute
adjustments for both elevation and windage. The sights could
have contributed to remarkable accuracy if the guns on
which they were mounted were equally capable. Some early
sights incorporated such advanced features as
• Rear apertures (tiny peepholes set close to the eye)
• Hooded fronts (a circular covering of the vertical bead or
post at the muzzle)
• Threaded adjustment tracks complete with calibrated
settings
All are advantages seen in the highest quality match sights
today (Figure 1).
Gun Sights
We can only guess at the effectiveness of the early sights, but
clearly some gun makers enlisted the age-old concept of
using two reference points to establish a straight line. The
old revelation is that you can “create” a straight line using
your eye to sight on two given points, be they sharpened
sticks, notched wood or pottery, or even pointy rocks.
Certainly early builders used such a fundamental sight
premise. By the time of the great Greek and Roman empires,
the science of surveying had developed the principle. The
principle is simple: After aligning two positive, stationary
references, it becomes possible to extend that line to a third
point. In the case of guns and shooting, that third point is the
target. Hence, the reliance on front and rear sights working
in tandem, even as we continue to use them today, is simply
recognition of an immutable law of physics. Each time a
shooter aligns front and rear metallic sights on a target, he
or she creates a line (Figure 2).
Metallic Sight Development
While the knowledge of sights was fairly widespread, the
great majority of guns through the end of the eighteenth cen-
tury had none. It’s unlikely that the early smoothbore mus-
Gun Sights2
FIGURE 1—Although this early matchlock rifle carries sights, it wasn’t very accurate.
FIGURE 2—The principle of extending a straight line from the eye through two fixed points and then on to a thirdpoint-the target-is the basis for all metallic sight functions.
Gun Sights 3
kets would have benefited from mounted sights. Great armies
of the line squaring off in pitched battle wielded these military
arms. The emphasis was on reloading speed and a high rate
of fire-not precision.
Early Hunting Sights
Perhaps the most common sights of the era were those found
on the better hunting guns, first the German Jaegers and
then American long rifles (Figure 3).
Compared to finely wrought examples occasionally seen on a
weapon made for some duke or prince, they were somewhat
crude fixtures. In their most common form, they consisted of
a shallow V- or U-shaped notch for the rear sight-the one
closest to the eye-teamed with a simple rounded bead front
sight positioned at the end of the barrel.
Even today, such a combination is preeminent, and is com-
monly referred to as an “open” sight. The shooter simply
centers the bead in the notch and imposes the alignment
over the target.
The Pivoting Ladder
Throughout the first half of the nineteenth century, the
function of rifles changed dramatically. Emphasis shifted to
accuracy, and with that shift came the proliferation of sights
on virtually every rifle. Long-range shooting became a much
more viable art that depended on adjustable sights. The rear
notch remained in vogue. However, by the time of the Civil
War, arms makers like Sharps, Maynard, Enfield, and
Spencer had addressed the adjustment demand by mounting
the notched sighting piece on a pivoting “ladder.”
FIGURE 3—Sights like the ones mounted on this early American long rifle were rather crude fixtures.
By raising the ladder (which actually served as a track for a
sliding notched crosspiece) up off the barrel, the rifle would
place its shots higher, that is, achieve impact at longer dis-
tances. The adjustment simply required that the shooter
elevate the muzzle to align the sights. Thus, the ladder-type
rear sight, marked off in graduated settings that indicated
the increasing range, made it possible to shoot quite far with
reasonable accuracy. Indeed, some sights of the post-war
years were calibrated to 800 yards or more.
A ladder (sometimes referred to as a “leaf,” though that term
more frequently designates any notched sight piece) could be
attached to the gun and worked in different ways. Perhaps
the most recognizable type was hinged at the rear and was
simply stood up vertically for use. The sighting notch was
held in place by a set screw or spring-loaded “ears” that were
squeezed to free it to move to another setting.
Tangent Sight
Another ladder/leaf style worked on a lever principle (Figure 4).
In this type the sight leaf serves a dual purpose: its notch is
built in as a fixed end piece, and it acts as a guide for a slid-
ing jack. As the jack moves forward in contact with a ramp-
like base, the entire piece angles upward. The closer the jack
gets to the top of the ramp, the greater the elevation of the
rear sight, and consequently the shot. It’s easy to see how
this type is braced more rigidly, and therefore is more durable
than the pivoting ladder. Both designs proved so useful that
in some form they were continually employed into the modern
era on such advanced rifles as the 1903 Springfield (vertical
type) and Mauser 98 (vertical and ramp combined).
Gun Sights4
Gun Sights 5
The Aperture or “Peephole” Sight
Shooters soon devised another way to use the ladder sight,
this time as an elevator for a sliding peephole, or aperture.
Somewhere along the line they learned that sighting through
a small opening positioned close to the eye produced excel-
lent results. The rear sight no longer obscured a significant
amount of the field of view-so long as the peep was large
enough and/or close enough. Even better, the eye reacted
naturally to the peep, centering itself instantly while looking
through to the front sight and target beyond (Figure 5).
In all two-component sight systems, the front sight must be
the primary focus if the sights are to deliver their inherent
accuracy. While the peep won’t compensate for poor shooting
fundamentals, it does make sight alignment largely an auto-
matic process. By all accounts, peep sights were and still are
the fast track to accuracy.
Perhaps no one has used peep sights to such devastating
effect as the buffalo hunters. To get the peep close to the eye
where it would do the most good, they mounted the folding
ladders on the tang straps of their heavy Sharps and
Springfield rifles. Attached to and sliding on the ladder was a
rather large, coin-like metal disc drilled with a tiny hole.
FIGURE 4-This Mauser “foldingleaf” or “ladder” is typical ofthe type outfitted on militarybolt-action rifles in the yearsleading up to World War II. Youcan adjust elevation to morethan 1,000 yards.
From ranges up to 1,000 yards, the professional hunters
employed these rifles and tang sights to slaughter the bison
with terrible efficiency.
Eventual improvement came to tang sights by substituting a
solid stem for the traditional ladder. The peephole was then
mounted on the stem or incorporated into the design as a
rounded end piece. The stems were usually threaded and
set into a knurled sleeve, which was turned to make very
exact elevation adjustments. At the pivoting base was a
screw that moved the peep laterally to adjust for windage.
This type of sight was often mounted on the turn-of-the-
century Winchester and Marlin lever-actions where it
complemented the standard-issue open sights.
Metallic Sights for Modern Rifles
Before continuing the discussion of later peep/aperture
sights, we should consider two other developments. The first
is the front sight, which takes a few basic forms: bead, blade,
post, or aperture.
Gun Sights6
FIGURE 5—Aperture sightsare prevalent among competi-tive shooters because theytend naturally to center thefront sight as well as sharpen-ing the focus. The micrometerfine-tuning on this model iscapable of 1/8 minute-of-angle (1/8 inch at 100 yards) adjustments.
Gun Sights 7
The Front Sight
Small, rounded beads are the most common front sights.
You’ll sometimes find them used with one of the other types-
for example, when mounted atop a blade. The blade and post
are very much alike, both appearing as thin rectangles rising
at the muzzle. The blade simply comes to an edge while the
post is flat-topped. The front aperture, also called globe front,
is a thin ring.
While you’ll encounter almost any combination, it’s often
helpful to mate front and rear sights with complementary
profiles. When using a U-shaped rear notch for example, the
rounded bead is a good match, for it appears as a ball floating
in an oval field. This combo works well for hunters who have
to line up shots quickly, though it does have range limitations
and tends to obscure much of the target. A V-notch works
well with a sharp blade to make relatively fast, accurate shots
at longer ranges by covering much less target. A post is the
right shape for a square notch when sight alignment is diffi-
cult. It’s also appropriate when the target is so close or so
large that it matters little if quite a bit of it is blotted out. The
post is a favorite of pistol shooters. Front and rear apertures
team up to make concentric circles around a bulls-eye, a
rather specialized sight that’s ideal (and intended) for compe-
tition shooting. The idea with all types is to present the front
sight perfectly centered in the rear opening.
We should point out that other arrangements of such vari-
ables are useful and popular in certain situations. The
aperture-and-post has been the standard arrangement on
U.S. military rifles for almost a century, providing soldiers
with an uncluttered field of view and a front sight that’s
substantial and easily seen.
Making the front sight more visible has always been a concern.
Held out away from the eye, front sights that are usefully
small tend to fade as the light dims. For hunters who use
metallic sights, the ability to see the front sight largely deter-
mines their time in the field.
Since the early days of metal sights, shooters have doctored
their front sights by various means to make them brighter. A
common strategy has been to inlay a post or blade with some
luminous material like brass, ivory, or recently, plastic.
Beads made entirely from these substances also help to
solve the problem. Today’s shooters often resort to white
or Day-Glo orange paint on the rearward face.
The problem with all such remedies comes when the sun is
strong and the reflection from a bright front sight produces a
glare that makes it difficult to see. This is something that can
also occur with very shiny blued sights. Match shooters, sub-
ject to eye fatigue during long events, insist on nonreflective
sights and sometimes dull theirs with lampblack, a blacking
agent, or by scorching them with a lighter.
Another approach is a sight hood such as the one used to
support front aperture rings, so long as it’s big enough to
permit plenty of light (Figure 6).
Competition rifles often carry both blackened sights (which
contrast nicely with light-colored target sheets) and hoods,
while a hunting gun may benefit from a hood combined with
a luminous bead or blade. Many military rifles, including the
M1 and M16, come with upraised “wings” that shield the
front post without actually hooding it.
Gun Sights8
FIGURE 6—Globe front sightsare the perfect complementfor aperture rears. Hooded toprevent distracting glare, theycan be fitted with a widerange of inserts. The ring orfront aperture insert is idealfor centering round bulls-eyes.
Gun Sights 9
The Rear Sight
The second development to consider is the many variants
of the basic notched rear sight leaf. So far, we’ve simply
referred to notches’ general outlines, but it’s also important
to note the specialized forms some have taken, particularly
the ones still being used today (Figure 7).
The buckhorn sight. A distinctly American rear leaf, with
a wide following in the early days of lever-actions, was the
buckhorn. This sight got its name from sides that curved
up and in, vaguely copying the shape of white-tailed deer
antlers.
Rather than a simple notch, the buckhorn sight design left a
large central opening (sometimes including a tiny “V” at the
bottom). In a sense, the buckhorn attempted to combine the
notch and aperture, but from its customary forward mount
atop the barrel it tended to cover up too much of the target.
An improvement to this approach was the semi-buckhorn,
which begins to copy the shape but has much shorter “horns”
that don’t curve inward and form a broad “U.” Today’s rear
sights sometimes consist of a semi-buckhorn-shaped frame
onto which various exchangeable leaves with varying notches
attach.
The express sight. Another variation on the notched leaf
is the express sight, which offers an even wider taper than
the semi-buckhorn. It takes the form of a very shallow “V,”
whose sides run out to the corners at an extreme angle. As
the name suggests, the express is the fastest metallic sight to
bring into use, though it’s somewhat lacking when a shooter
requires long-range precision. The express sight’s speed,
however, has made it the top choice for hunting dangerous
game at close range. The finest English doubles (and other
large-bore rifles) frequently have very elaborate express
FIGURE 7—Rear sight blade styles include (from left): express, buckhorn, and semi-buckhorn.
sights containing a number of folding leaves. Arranged in
increasing heights, the leaves enable the shooter to select the
correct one for a particular distance. Meanwhile, the higher
leaves for longer ranges remain folded flat against their
mount. The mention of express sights is synonymous with
African hunting.
Most rear leaf sights are adjustable for elevation but only the
better ones for windage too. Commonly, if windage adjustments
are available, they’re built into the mount. Usually, a spring-
tempered base lies horizontally along the barrel and is fixed
by screws or a dovetail union at its forward end. The rear of
the base may not be attached, but spring tension holds it
down.
You adjust the elevation by forcing the spring arm upward.
Sometimes you can insert a screw, lifting the base as it
turns, but more often you change elevation by pushing a
stepped wedge under the sight. Other times you angle the
base upward and the fitted leaf simply slides forward and
locks with a screw.
When you use exchangeable notched blades, the screw holes
provided for their attachment elongate to supply the adjust-
ment. All of the adjustment provisions work adequately, but
many lack precise index marks to facilitate quick return to a
certain elevation.
When windage adjustment is provided, you can usually
achieve it by driving the entire sight-mount included-one
way or the other in its dovetail slot. This adjustment is drift
adjustment, and it’s the most common way for adjusting a
front sight.
Occasionally, you can laterally manipulate a rear leaf sight
with a screw. When this is the case, more precision is avail-
able than when using the drift method.
Rear leaf sights have always served their purpose reasonably
well. To this day, manufacturers outfit most factory rifles
with them. They’re often dressed up with a white triangle
or diamond pointing to the sight notch. No doubt, this has
made them even faster to use. As previously mentioned,
however, savvy metallic sight shooters long ago realized the
advantage of placing a peephole or aperture close to the eye.
Gun Sights10
Gun Sights 11
This realization triggered the development of sophisticated
yet versatile rear aperture sights that you could adapt to
practically any kind of modern rifle.
The Cocking-Piece Sight
With the advent of bolt-actions that offered no tang for
mounting, aperture discs and rings moved forward. Early on,
there was the cocking-piece mount, which attached directly
to the moving bolt plunger on rifles like the ‘03 Springfield,
the Krag, and the Mauser. Cocking-piece sights were essen-
tially scaled-down versions of tang-mounted sights, but even
the lightest model slowed the rifle’s lock time, thus negatively
affecting accuracy. Accuracy was further compromised
because the sight was mounted on a moving part and really
didn’t occupy a consistent position shot-to-shot. Moreover, it
was nearly impossible to practice good follow-through and to
call one’s shots when using a sight that jumped away.
Cocking-piece sights had their fans for several decades, but
by the 1950s they pretty much faded from the scene.
The Receiver Sight
A rear aperture style with much more staying power is the
receiver sight. As its name indicates, this sight mounts on the
receiver, usually as far to the rear as possible. Both hunters
and target shooters embraced it. Today, however, the scope
has just about made the premium metallic sights obsolete for
hunting. Still, a visit to any bulls-eye rifle shoot confirms
they’re still alive and well when not competing with scopes.
It’s the rare match shooter who tries to compete with any-
thing but precision receiver sights (Figure 8).
Several decades back, the development of receiver sights for
hunting and target shooting took different directions. In gen-
eral, the hunting models remained compact and rugged and
possessed fewer parts than the sophisticated match versions
with their built-in micrometer adjustments, calibration
scales, and eye shades.
Gun Sights
Aperture size and the way it’s presented to the eye are also
major differences. Hunters want a fairly large aperture that
allows them an unobscured view, and at the same time don’t
want available light limited any more than necessary. For
them, a peephole about inch in diameter, surrounded by a
narrow rim, is probably the best bet. Match apertures are
considerably smaller-.05 inch is a common size and some are
even tinier. Competition sights also change aperture size
quickly, either by accepting removable discs or by utilizing a
disk containing an adjustable aperture similar to those found
in camera lenses. Changing discs and adjusting the aperture
size enables shooters to meet range conditions.
Discs often come with an oversized light shield, or they’re
mounted inside a rubber eyepiece that blocks out all light
that’s not coming through the tiny hole. This also has the
effect of bringing the image of the target into very sharp
focus, again working like a camera lens.
The best receiver hunting sights were traditionally built on a
right-angle frame whose horizontal upper leg holds the aper-
ture out over the receiver in line with the bore. The vertical
leg extends down on one side where its mount attaches to
the receiver with screws. The entire unit remains extremely
compact, hardly two square inches.
Today, many of the same models are tailored to use top
mount screw holes, but they have the same low profile that
stands up to rugged use. Shooters often relied on such sights
as insurance not so many years back when scope durability
12
FIGURE 8—A great manyhunters once favored compactreceiver sights like this Lyman66. Besides being very light-weight and handy in heavybrush, they provided excellentaccuracy. Also, you can quick-ly remove many models fromtheir mounts when not in use.
Gun Sights 13
was still a dubious proposition. Adjustment knobs are pur-
posely down-sized so they won’t snag on brush or clothing.
Certain models feature a spring-loaded quick-release fixture
for removal from the mount base at the press of a button
(Figure 9).
Target aperture sights for smallbore rifles are fitted to mount
directly into grooves milled into the top of the receiver. Often-
times they sit relatively high above the bore line to correspond
with the elevated cheekpieces found on these rifles. Target
sights are comparatively heavy (6 1/2 ounces vs 1 1/2 ounces
for a hunting sight) and their large micrometer adjustment
knobs give positive clicks as fine as 1/8 minute of angle.
Installing Metallic Rifle Sights
At one time, the acquisition and installation of a new sight
were the most common reasons for visiting a gunsmith. To
some degree this is still true, although nowadays the request
is usually for scope installation. Unless the gunsmith works
closely with serious match shooters, the times the shooter
will ask the gunsmith to exchange a rifle’s factory metallic
sights for better ones will be few and far between. Nonetheless,
it’s a job that the gunsmith must handle with skill and preci-
sion if the sight is to perform up to its capabilities. Sloppy
work can permanently mar a gun, and while many shooters
can mount their own scopes, the general unfamiliarity with
metallic sights usually means that the shooter must turn the
job over to a professional.
FIGURE 9—Notice this receiv-er sight’s right-angle frame.
Prior to installation, you must determine the proper sight
height. For relative similarity between the point of impact
and aiming points, front and rear sights must be the same
height above the bore. To calculate the height, use a caliper
or micrometer to make three very exact measurements (preci-
sion is vital here, as a few thousandths of an inch could
make a big difference). Measure the barrel diameter at the
rear sight and divide by two. To this figure, add the meas-
ured height of the rear sight at the middle of its adjustment
setting. Then, measure the barrel diameter where you’ll
mount the front sight and divide by two. Subtract the for-
ward barrel figure from the rear barrel/sight sum and the
difference is equal to the required height of the front sight.
For example, say the barrel diameter at the rear sight is
exactly 1.0 inch. Divide by two to get .5 inch. Then, add the
height of the rear sight, which is .5 inch. At this point we’re
back to 1.0 inch. Barrel diameter at the front sight measures
.8 inch, which divided by two is .4 inch. Subtract .4 from 1.0
(1.0 – .4) to get a difference of .6. The overall height of the
front sight must be .6 inch.
In practice, you must build up the front sight to match the
relatively high position of the rear. When you mount a basic
rear sight leaf directly to the barrel, a front bead, blade, or
post similarly mounted is often sufficient. However, when
you elevate the leaf or use a different type of rear sight, it
becomes necessary to raise the bead/blade/post with a
ramp. You attach the ramp, a rectangular piece whose face
angles back toward the shooter, to the barrel, and then you
attach the sight to the ramp. Combined, the ramp and front
sight meet the height requirement with a much stronger and
better-looking fixture.
You may see a barrel with an integral ramp, usually the work
of a custom barrel maker. This adds considerably to the
effort of forging the barrel, and therefore considerably to its
cost. Fortunately, add-on ramps are widely available, and
some even have the bead or blade incorporated into their
design. The leading makers of metallic rifle sights like
Williams and Marble offer extensive selections of front sight
heights and styles to work with various rear sights on just
about any modern rifle.
Gun Sights14
Gun Sights 15
Metallic sights attach to a rifle in several ways. Rear sights
are either held in place by screws, friction-fitted into a dove-
tail slot, or soldered (silver or soft depending on the sight and
gun) to the receiver or barrel. Front sights are secured by
screws, dovetails, and soldering as well, and in addition, a
blade or post may be inserted at the muzzle in a linear slot.
You frequently cut dovetail sight slots directly into the barrel,
but you may also machine them in a mount base joined to
the barrel by screws or an encircling band. Some front sights
are even fabricated with the bead/blade, a ramp, and the
band as a single made-to-order unit.
When substituting a new sight that’s the same type as the
old one, the gunsmith can almost always use the existing
screw holes or dovetail slots. You should check them, of
course, to make sure they’re in good condition; the threads
must be intact, and dovetail corners must be sharp. In cases
of extreme wear, retapping a hole or dressing corners with a
file may be necessary.
At the outset of any sight exchange work involving dovetail
mounts, remove the barreled action from the stock and brace
it in a padded vise. (This may also be necessary with certain
screw-on mounts.) Such reinforcement prevents possible bar-
rel damage. Always drive the old dovetail mount out from left
to right with the muzzle pointed away. Use a soft brass drift
punch or a nylon rod for all driving and tap only as hard as
necessary to move the sight.
With dovetails, mark the barrel with a felt-tip marker pen to
record the center point of the old sight. Make a correspon-
ding mark on the new sight, then drive it in-right to left-until
the two marks are just short of meeting. Make the final drift
adjustment after firing a few shots (preferably at close range,
say 10-15 yards), tapping it only as far to the left as needed
to line up the windage. This saves wear on the slot caused by
driving the dovetail back and forth and will ensure that the
sight remains sufficiently tight. If the fit of a new sight is a
little loose, use a coating of solder tinned to its bottom sur-
face to take up the slack. Be sure to file the solder smooth
before installation and clean up the edges afterward.
Gun Sights16
For some sight mounting jobs it will be necessary to provide
a dovetail slot where none currently exists. It is best, when
cutting a dovetail into a barrel or receiver, to use a milling
machine and the properly sized sight base cutter. The stan-
dard for rifle sights is inch with a 60 degree shoulder.
Machine tools aren’t an absolute necessity; however, you can
fashion a perfectly acceptable dovetail with a few hand tools.
However, you must do it with extreme care, and many gun-
smiths disdain making this alteration to a gun. Their feeling
is that it weakens the barrel and so doing causes it to vibrate
much more than usual, thereby reducing accuracy. As an
alternative, you can provide dovetail slots by substituting
screw-on or sweat-on (soft solder) bases or a barrel band
precut with dovetails. Nevertheless, because dovetail-mounted
open sights remain prevalent, we’ll now describe the
procedure.
Installing Dovetail-mounted Open Sights
Sight dovetails have the standardized dimensions of .090
inch deep and .375 inch wide along the lower face. Before
getting started, measure the barrel to ensure that it’s thick
enough to take the cut. You should leave as much metal
above the bore as you plan to take away.
It’s important that you make the cut exactly perpendicular to
the bore. The easiest way to do this is by snugging the barrel
in a padded vise, then rotating it until the existing rear sight
is level (check with a machinist’s level). If this isn’t possible,
use a pair of try squares to true the action vertically. Rest
the head of one square on a level surface and align its blade
with the blade of the other square. Then, rotate the barrel
until the flat underside of the receiver lines up with the head
of the second square.
For clean, precise hand cuts we advise you to employ some
kind of guide tool, such as the SPL Dovetail Guide (Figure 10).
This is a handy, square-sided device that clamps onto the
barrel and offers an open tooling slot on its top face that’s
perfectly sized (depth and width) and angled for dovetail
dimensions. Its flat sides simplify leveling and the hardened
steel prevents overcutting. The user merely makes cuts
(described below) through the slot.
Gun Sights17
In the absence of a machined guide,
begin by measuring the narrowest part of the sight dovetail
and transferring this dimension to the barrel using a sharp
scribe. Use a try square to ensure that you make the scribing
marks squarely on the barrel. Even better is to inscribe the
dovetail’s entire profile on the barrel. At this point, just
enough of the barrel’s upper surface should project above the
vise jaws so that the jaws help regulate the depth of the cut.
Use a hacksaw to begin the metal removal.
Caution: Be sure not to penetrate to the full .090 inch depth.
Make several of these closely spaced, short hacksaw cuts
inside the scribing marks.
You remove the remaining steel and shape the dovetail with
a 60 degree, 3 square file. It’s best to grind one side of the
file smooth beforehand
so that only one sur-
face is cutting at any
one time and turn
down the smooth side
(Figure 11).
FIGURE 10—The SPL DovetailGuide helps you cut clean andaccurate dovetails every time.
FIGURE 11—After carefullyscribing the outline on the barrel and making a number of initial cuts with a hacksaw,you shape a dovetail sightmounting slot with a 60 degree file. At least one side of the file should be smooth to avoid unintended cutting.
Ideal for cutting dovetails is Brownell’s Sight Base File, spe-
cially made for this job. It comes with just one cutting face;
the other two sides are smooth, eliminating the possibility of
unintentionally enlarging the cut. Undercut both sides grad-
ually, switching from one to the other to make sure they stay
even, and as the slot takes shape, closely compare and fit
it to the actual sight dovetail. Keep in mind that the slot
should taper a tiny bit-the final cuts make the right side a
few thousandths of an inch wider to ease the dovetail in and
out of the cut.
Many rear aperture sights are side-mounted to the receiver
wall with screws, except on certain match rifles where receiv-
er top grooves have been provided. It’s vital that you install
the mount square to the receiver so that the aperture arm’s
position is exactly perpendicular to the bore. The location of
the mounting holes governs this. Ideally, you locate, drill,
and tap screw holes using a professional jig setup like the
Forster Universal Sight Mounting Fixture or Brownell’s SSR
Mounting System. These tools ensure correct alignment with
the bore, square screw holes to the action, and guide drills
and taps with hardened bushings so that the holes are clean
and straight. When a drill jig isn’t available, it’s possible to
square the sight base to the receiver with a try square. Place
the square’s head on the true undersurface of the receiver
and line up the base with the blade. Clamp the base securely
in this position with a C-clamp, and scribe the location of
one of the holes. Remove the base and center punch the
mark, then drill the hole with a No. 31 drill and tap for a
6-48 screw. Install the sight, tightening the screw firmly.
Now, use a No. 28 drill to mark the spot of the second hole.
It will center in the sight base hole, thus ensuring precise
registration with the first hole. Don’t overdo it with the No.
28 drill-just enough to provide a center. Then remove the
sight, center punch, and finish drilling with the No. 31. Tap
the hole and install the sight.
Caution: Only use hollow-ground screwdrivers with parallel-
sided blades and be certain that the blade completely fills the
screw slot. If you don’t have the correct blade, grind one to
fit. A mismatched screwdriver blade invariably jumps the
slot, thus damaging the screw head and scratching the metal
finish. Screws extending through the receiver wall must be
Gun Sights18
Gun Sights 19
filed flush. Use a quarter-inch rattail file for this and finish
with a piece of emery paper wrapped around the file.
All sight-mounting screws should be extremely tight and
coated with a few drops of Loc-Tite or a similar thread-locking
compound before final installation. Use sparingly and wipe
away any excess before it has a chance to seep onto other
surfaces or parts.
Although it’s permissible to drill into receivers when mount-
ing sights, you should never penetrate the bore when drilling
holes for barrel sights. Quite simply, this ruins the barrel.
It’s essential to determine how deep the hole can be in a
given spot. This may change from one end of the barrel to
the other since many have thicker walls at the breech than
at the muzzle. Prior to any drilling operation, measure the
barrel thickness at the spot you’ll drill using a caliper,
divider, or micrometer where possible.
Most quality drill presses come equipped with a depth-
indicator scale. It’s a good practice to set up the drill so
that it can penetrate no deeper than 1/32 short of the final
desired depth. Take great care when drilling barrel-sight holes,
checking frequently with a high-quality depth micrometer.
The optimum holding power of a 6-48 screw is attained at
.137 inch; for the 8-40 it is .162 inch.
In thin-walled barrels, it’s not always possible to provide this
much internal thread while taking care that the screw doesn’t
bottom out in the hole. Carefully note where the screw head
is when the screw begins to tighten. If it’s not fully seated
against the sight body, remove the screw and carefully grind
a little off the end.
Sweat-on (soft-soldered) sight bases and ramps will often be
reinforced with a screw, but it’s the heat-bonding of the met-
als with the solder that’s intended to secure the sight.
However, there are few things to keep in mind when using
this method to install sights. Foremost, you must mount the
bases squarely to the barrel. To do so, true the barreled
action in the vise with try squares as previously described.
Place the sight in its approximate location on the barrel and
use a level to determine its exact position. Scribe the outline
of the base on the barrel as a guide for the sweating operation.
It is best to use a sight/ramp soldering jig as offered by
Brownells and other firms to maintain the necessary constant
pressure during heating. It’s difficult for a standard C-clamp
to prevent sight-base slippage when the solder softens. Remove
excess solder with a rag and check to make absolutely sure
the sight is level before the joint begins to harden.
Zeroing and Adjusting Metallic RifleSights
One fundamental principle governs sight adjustment: Always
move the rear sight in the direction that you want the shot
to move. If, for example, a shot group prints to the left of
the bulls-eye, move the rear sight to the right; when shot
placement is low, raise the rear sight. When you apply this
principle to open or aperture rear sights, it means that you
must move the sighting notch or peephole. Conversely, on
those occasions where it’s necessary or preferable to adjust
the front sight, you must move it in the opposite direction of
the desired impact change.
Some open and rear-leaf sights are dovetail mounted and
have no provision for adjustment other than drifting the
dovetail in its slot. This adjusts for windage only. You make
drift adjustments the same way that you remove an old dove-
tail-by driving the sight with a mallet and brass or nylon
punch. Not only is this a very inexact technique, it could
damage the rifle if the shooter doesn’t take pains to do it
right.
When making windage adjustments, avoid marring the stock
or metal finish by first laying the rifle on a table or bench
covered with a rubber mat or old carpeting. Rather minute
changes in the sight’s position can produce significant shifts
down-range, so tap the sight lightly and move it only a little
at a time.
Elevation adjustment for most open sights is controlled by a
screw or a notched sliding elevator. Occasionally a sight is
made to take replaceable leaves that you can shift up and
down in their oblong screw slots. All of these are fairly easy
to use, but the shooter must work with them to become
familiar with the impact changes they produce. Understand
Gun Sights20
Gun Sights 21
too that elevation is set for a particular distance, so shots
will no longer be zeroed when firing at longer and shorter
ranges.
The key to adjusting open sights is to patiently make the
adjustments in very small increments. Also, it’s wise to begin
the sighting-in process at very close range-certainly no farther
than 50 yards-and on a rather large target. Most experienced
shooters prefer to adjust windage first. That way the shots
are hitting on the target’s central axis. The good thing about
zeroing open sights is that they are very sturdy and probably
won’t need to be dealt with again so long as the shooter and
load remain the same.
Whether for hunting or competition, rear aperture sights are
usually designed with precise adjustment capability. This
makes them easier to zero than open sights. Because they’re
inherently more accurate, the shooter usually needs to fire
fewer sighting-in shots than is required for open sights
(Figure 12).
Aperture sight adjustments are calibrated to provide impact
shifts in a fraction of one minute-of-angle, a geometric unit
for measuring a circle. For the shooter, it’s necessary to
understand that one minute-of-angle nearly equals one-half
inch at 50 yards, one inch at 100 yards, two inches at 200
yards, etc. When sights adjust in one-quarter minute clicks,
the practical effect is to change shot placement one-quarter
inch at 100 yards, one-eighth inch at 50 yards, one-half inch
at 200 yards, and so on. (One-quarter minute clicks is the
FIGURE 12—A multileafnotched rear-sometimesreferred to as an express sightwhen found on large-caliber“safari rifles”-is the mostsophisticated type of opensight.
most common degree and terminology for such increments.)
If, for example, a 100 yard shot group is two inches high
and 11/2 inch left, the shooter would zero it by rotating the
adjustments knobs to move the aperture down eight clicks
and right six clicks. Suppose the group is off-target by the
same amounts at 200 yards. Then it would take four clicks
down and three right to put the shots in the bulls-eye.
Be aware that not all aperture sights offer quarter-minute
adjustments (half-minute and eighth-minute are also avail-
able). Also be aware that the adjustment values are usually
figured on a 30 inch sight radius (the distance between front
and rear sights). When the sights are closer or farther apart
than 30 inches, the values will differ. Also, some less sophis-
ticated models may adjust by means of a sliding scale held in
place with a set screw rather than click-type knobs.
When the shooter learns what to expect from the adjust-
ments, he or she is able to use them quickly and efficiently
to allow for wind or additional range when hunting or in
competition. Because the knobs and scales are marked, the
shooter can quickly return the sight back to its original set-
ting. Again, it’s wise to sight-in at 50 yards or less first, then
correct for the desired zero range by moving the target and
firing at that distance.
Gun Sights22
Gun Sights 23
Self-Check 1
At the end of each section of Gun Sights, you’ll be asked to pause and check your under-standing of what you have just read by completing a “Self-Check” exercise. Answering thesequestions will help you review what you’ve studied so far. Please complete Self-Check 1 now.
Indicate whether the following statements are True or False.
_____ 1. To get peep sights closer to the eye, buffalo hunters mounted them on the tangstrap of their rifles.
_____ 2. When zeroing metallic sights, you should begin the shooting at 50 yards or less.
_____ 3. The aperture of a target competition receiver sight is usually quite large.
_____ 4. You should taper a dovetail sight mounting slot so that the left side is a few thousandths of an inch larger.
_____ 5. In essence, when a shooter aligns front and rear sights, he is creating a straightline to the target.
_____ 6. To make front sights more visible, shooters have resorted to moving them closer tothe rear sight.
_____ 7. German target shooters were using front and rear rifle sights as early as 1700.
_____ 8. The development of ladder-type rear sights made it possible to sight-in for as far as800 yards.
_____ 9. On certain sight mounting jobs, it’s necessary to drill into the rifle’s bore.
_____10. Front sight styles include express, buckhorn and semi-buckhorn.
Check your answers with those on page 97.
HANDGUN SIGHTS: PRECISEALIGNMENT
In no type of shooting is it more important and as difficult to
use the sights properly than when firing a handgun. We can
sum up the reason for this in an oft-heard pistol shooter’s
phrase-short sight radius. As noted in the section on rifle
sights, sight radius simply means the distance between front
and rear sights. Obviously, this distance is much shorter on
a handgun. Consequently, there is far less room for alignment
error since it only stands to reason that any variance magni-
fies the barrel’s angle off the intended aiming point. The
result down-range is inaccuracy.
As difficult as it is to attain proper sight alignment with a
handgun, it’s probably even harder to maintain it. A firearm
held out in front of a shooter will just never be as steady as
one braced against the shooter’s body. Though handguns are
every bit as old as long guns, perhaps even predating them,
the inherent problems of shooting them with any degree of
accuracy effectively stymied the development of their sights. It
was probably a foregone conclusion that these fast-handling,
easy-carrying guns were to be relegated to point-blank duty
and we couldn’t expect much more of them. This isn’t to say
that early handguns didn’t have sights. Many muzzle-loading
pistols were outfitted with front bead and perhaps some type
of rear notch or even both. No doubt these sights made them
far more serviceable. Still, muzzle-loading pistols and the like
weren’t much good any farther than one could throw them.
Fixed Sights
Not until the introduction of Colt’s cap-and-ball revolver
design and others like it did utility come to pistol sights. These
revolvers weren’t immediately more accurate than single-
shots of the time, but their ability to fire several shots rapidly
led to enhancements for making those shots more consistent,
one to the next.
Gun Sights24
Gun Sights 25
The early revolvers evolved with a sight setup that remains
the basic offering to this day. It originally consisted of a
small notch in the hammer for the rear sight and a thin
half-moon blade stuck to the barrel for the front sight. This
setup slightly improved when a shallow rounded groove in
the top of the frame became the rear sight.
Such sights are fixed. No adjustment is possible other than
visibly changing the sight picture or filing down the front
sight to move shots higher. (Remember, moving the front
sight up or down-in this case down-results in shots moving
in the opposite direction.) Because these open sights lack
adjustment capability, they pose certain problems for the
shooter. It becomes difficult to change loads, to shoot in
wind, or to cope with much variation in range. If for some
reason the gun doesn’t shoot well, it’s hard to ascertain if
the sights are to blame. Nevertheless, these sights are utterly
durable and the shooter can’t “rough” the off zero. Also, they
in no way hamper the shooter when drawn from a holster
or pocket. Furthermore, there have been countless revolvers
and small automatics over the years that have been
admirably accurate with such fixed open sights. We should
note also that aperture sights never caught on for handguns,
since the shooter’s eye is too far away to make much use of
a peephole.
In the late 1800s, when target shooting with all kinds of
guns was a sport that attracted widespread interest, there
emerged developments in handgun sights that had a pro-
found influence. Two top pistol competitors, Ira Paine and
E. E. Patridge, promoted distinctive designs, sometimes even
referred to as “Paine” or “Patridge” sights. You’ll find both
of these, or at least close derivatives, on a majority of the
handguns in use today.
The Paine Sight
The original Paine-type sight teamed a U-shaped rear notch
with a bead front. While the U notch remains quite common,
it’s rare to see a bead on handguns these days, and blades
(of many different shapes and sizes) are the clear choice of
contemporary pistol makers and shooters. On some current
models, the notch is built up off the frame in an integral pro-
jection or a soldered addition, and its shape may now be a V
or square. Whatever the variation, the blade front and fixed
notched rear remain as basic factory equipment on a wide
range of handgun models. It’s especially prevalent on smaller
pieces intended solely for very close range work (Figure 13).
The Patridge Sight
The Patridge, which remains quite popular with many hand-
gunners, match shooters in particular, is fundamentally
identical to its earliest versions. It offers a square or rectan-
gular rear leaf bearing a square notch. The front is a blunt,
high, flat-sided post that’s often (but not always) perpendicu-
lar to the barrel. E. E. Patridge felt that the sharp angles on
top and the narrow clearances between the post and each
side of the notch would give the fastest and most precise
sight alignment so crucial for a short-barreled gun.
Apparently he was right, for the Patridge system dominated
pistol competition for many years until the use of optical
devices superseded it. Even now, when the rules dictate
metallic sights, a Patridge front blade working with an
adjustable rear is the hands-down favorite.
Gun Sights26
FIGURE 13—Two enduringtypes of handgun sights arethe Paine (top), a shallow U-shaped groove and a frontbead, and the Patridge (bot-tom), with its high square-notched blade and squarefront post.
Gun Sights 27
Adjustable Sights
Match shooters were quick to demand adjustable sights, and
the gun makers soon responded. Companies like Colt and
Smith & Wesson devised sights (both front and rear) that
pivoted by some means and were held in place by set screws.
The shooter adjusted rear windage by manipulating a pair
of screws at either side of the sighting notch. At times it took
much perseverance to zero early adjustable sights, but they
could be made to shoot quite well and gave pistols a versatili-
ty they hadn’t previously possessed.
Where the first adjustable pistol sights were probably some-
what fragile, those that followed and the ones used today are
compact, rugged, and not likely to be thrown off zero even
with rough treatment. In their most basic form, current
adjustable pistol sights can only move laterally, usually by
the drift method, and therefore can only correct windage.
These aren’t for match shooting, of course, but you’ll find
them on many mid-size and larger revolvers and some auto
loaders, including many police and service weapons.
The better adjustable rear sights are now capable of fine-
tuning both windage and elevation (w&e), some even incorpo-
rating miniature micrometerlike mechanisms. Quite a few of
the factory w&e sights appear as compact cylindrical attach-
ments supporting notched sight leaves. Others, particularly
aftermarket offerings, are contained in low-profile, square
housings. On both styles, you make windage and elevation
corrections by turning separate adjusting screws, some of
which feature positive felt clicks like the ones in rifle receiver
sights and scopes.
When w&e rear sights are factory installed, they’re most likely
on the pistol maker’s top-of-the-line models. The finest of
these include Smith & Wesson’s factory rear sight and custom
versions from companies like Millett, MMC, Bo-Mar, and
Wichita. Obviously, they’re on the firing line when the top
bulls-eye, silhouette, and combat pistol competitors are
using metallic sights.
Dots, Outlines, and Inserts
Not an especially new idea but one that remains timely today
is the notion of adding some type of bright reference marks
to pistol sights. These can be valuable when shooting in dim
light, so they’ve been particularly useful for handgun hunters
and police.
Dots, which are usually white (alternately red or orange), can
be on either side of the rear notch and on the face of the front
post. Outlines are inlaid white or gold lines that highlight the
shape of the notch and occasionally extend up or form a cross
at the center of the post’s rearward face. Inserts, traditionally
made of brass or red plastic, are set lengthwise into a front
post and flush with its face. These also come in white, yellow,
green, and orange.
You should understand, however, that none of the high-
visibility markers actually define the true sight picture. All
are situated off the notch’s or post’s sharp black edges,
which must be finely aligned for ultimate accuracy. The
dots, outlines, and inserts function as guides that enhance
and speed up the alignment process.
Glow-in-the-dark Sight
Working on the same principle are ultrahigh-tech glow-in-the-
dark sights developed for military and law enforcement use.
These get their “glow” from a built-in source of tritium gas
that makes luminous dots or outlines. Conversely, glare from
any sight or visible surface can blur sharp edges and make
precise sight alignment impossible. To prevent this, most
sight surfaces that face the shooter are grooved, serrated,
beveled, or even checkered so that they can’t reflect distract-
ing light. Like rifle competitors, handgunners will dull sights
with lampblack or commercial blacking agents to eliminate
glare.
Gun Sights28
Gun Sights 29
Ribs
Originally a feature found on shotguns, rail-like attachment
ribs for pistols and revolvers provide a handy means for affix-
ing sights. Performing as on shotguns, they guide the eye
down the barrel to speed front sight acquisition. Ribs extend
along the top of the frame/barrel or slide in a wide selection
fitted for specific handgun models. Many ribs come outfitted
with top-quality adjustable front and rear sights, though they
can also be solely a mounting rail.
In an extreme application, international free pistol shooters
use a rib-like extension to position the front sight well out
ahead of the muzzle. This gives them extra sight radius,
which translates to increased accuracy. It’s obvious that
such an unwieldy appendage is impractical and undesirable
for handguns outside this highly specialized sport, but it
does show how ribs provide a gun more sighting versatility.
Installing Handgun Sights
Among handgun owners, a fair number will want to swap
factory sights for new ones. They’re certainly not in the
majority and generally won’t include casual plinkers or
one-gun householders whose pistol represents a means
of emergency self-defense. Furthermore, handgun hunters
these days are virtually unanimous in their adoption of
scopes. However, in places where target shooting is strong
or in shops that service police, security, or military personnel,
there will be a steady call for replacement sights. Also, heavy-
recoiling calibers and magnums that are fired a lot have a
tendency to shear small pins and screws in rear sight mech-
anisms, or to “shoot” loose front blades.
As with metallic rifle sights, there are a handful of common
installation methods. These include dovetail friction mounts,
screw attachment, soldering, and staking. Any of these meth-
ods will also work when employing a rib, although dovetail
and screw mountings are the norm. The ribs themselves are
usually affixed by a combination of dovetails, screws, and/or
soldering.
Fixed-sight pistols will rarely be subjects for rear sight
replacement since the original fixtures are virtually inde-
structible and the purpose of these guns make them unlikely
candidates for such customizing. However, in cases where
a shooter desires an alteration, one must devise a way to
attach a sight leaf to the existing rear sight. Where projecting
“ears” or some sort of sight leaf is present, you may be able
to solder a new leaf to the old one, filing the notch as
desired. On early Colt revolvers and others whose rear sight
is a basic top-strap groove, you must make a vertical relief
cut with a Dremel tool or small hand grinder to have some
flat surface on which to solder the new sight. This cut must
match the contour of the groove, not going too deep into the
frame lest the top-strap become weakened.
A much more likely scenario is to leave the rear sight intact
and replace the front. When the front sight is an integral bar-
rel forging, as on older Smith & Wessons, you can partially
ground it down to form a base. Then, slot it lengthwise to
accept a new blade. Make the slot initially with a hacksaw,
then widen and finish the cut with needle files. File-fit the
slot to the blade, extend it all the way down through the
base to the top of the barrel, and leave it a little tight. For
an extremely rigid installation that won’t loosen when you
shoot, secure it with a pair of hardened 1/32 inch drill-rod
pins driven through the base. (To do so, it will be necessary
to seat the blade first, then drill the pin holes.)
To replace Colt front sights and others that are soldered/
brazed into a barrel slot, it will be necessary to remove all of
the old blade at the outset. When any of it is still present-no
matter how little-grind off whatever remains above the barrel
and clean out the slot with a file. It’s then simply a matter of
inserting and silver-soldering the new blade in place.
Slot-mounted front sights are also common additions to
semiautos when you need more height to complement the
installation of a new rear sight. The latest versions are usually
rectangular, ramplike posts outfitted with perpendicular
mounting tenons that extend down into the slide. When no
slot previously exists for this installation, you can start one
by drilling a series of overlapping 3/32 inch holes just slightly
narrower than the width of the tenon. Join the holes and
Gun Sights30
Gun Sights 31
shape and finish the slot by filing, taking care to keep the
opening just a hair undersize to ensure a rigid fit. Silver sol-
der the new sight to the slide; afterwards, trim off any part of
the tenon that protrudes on the inside. For extra strength,
you can use drill rod pins to anchor the tenon/slide union.
The majority of handgun sight installation jobs involve
adjustable rear sights. Match shooters are well known
for experimenting with different models, and because the
adjustable sights often incorporate moving parts, from time
to time they come in for repair/replacement.
Swapping one basic dovetail-mounted unit for another is the
simplest rear sight conversion. This involves driving the old
part out of its slot with a brass or nylon punch. Always drive
the part from left to right with the muzzle pointing away and
then file the new one in its place (Figure 14).
Among the current selection of aftermarket sights, one can
find adjustable rear models made to fit factory dovetails on
most American-made and many foreign handguns. This, by
far, is the easiest, strongest, and least expensive alteration.
It’s crucial that dovetail mountings on hard-kicking guns
like the .45 ACP, 10mm, and all magnum calibers maximize
bearing surface contact. Check this by coating the slot sur-
faces with lampblack or carpenter’s chalk, fitting the sight,
then noting where the sight did and didn’t make contact. File
FIGURE 14—When removing adovetail-mounted sight, alwaysdrive it out from left to rightwith the muzzle pointing away.These slots are tapered a bitto the right side to facilitateinsertion/removal.
down all high spots until you achieve uniform contact. It’s
also wise to employ a secondary attachment method for dove-
tail mountings. Some current sights come with set screws
that bear on the dovetail floor. Similarly, you can stake the
sight securely into the dovetail with a sharp prick punch.
Alternate methods include tinning with soft solder (be sure
to cover both slot and mount) or using the prick punch from
inside the slide or top-strap to raise dimples on the bottom of
the dovetail.
A growing number of semiauto shooters prefer low-profile
“combat” rear sights. These mount very low to the gun to
minimize quick-draw interference and come in fixed, drift
adjustable (windage only), and fully adjustable versions
(Figure 15).
Full-adjustment models can sometimes require significant
alteration of the slide since they may fit too far to the rear to
utilize the factory dovetail. This requires cutting a new dove-
tail and, often, removal of metal from the rearmost portion of
the slide to allow clearance for an overhanging sight leaf. You
should perform such operations on a milling machine, but
first you must fill in the original dovetail by arc welding or
with a tight-fitting dovetail blank. Use a 65 degree cutter-in
the appropriate width-to make the dovetail and an end mill
cutter for the clearance cut. Make certain not to remove any
more metal than is absolutely necessary to clear the rear
of the sight. For more details on milling machines, see the
study unit entitled Basic Metalwork and Machine Tool
Operation.
Gun Sights32
FIGURE 15—Low-mountedadjustable rear sights havemade handguns significantlymore accurate and versatile.The best models areadjustable for both elevationand windage and come withpositive, micrometer-like“clicks.”
Gun Sights 33
Another adjustable rear sight commonly chosen for upgrade
jobs is the Smith & Wesson type with its elongated, spring-
like mounting base. Millet Co. fabricates fitted versions for
many current revolver models (including one for older S&W N
and K frames) as well as the Colt Gold Cup auto loader. The
base extends along the top-strap or slide like a partial rib
and is neatly attached by a mounting screw (Figure 16).
On guns that don’t already have the screw hole present for an
existing sight, you must drill and tap one. Always disassemble
autos or remove revolver cylinders before any drilling opera-
tion. Secure the slide or frame in a padded drill press vise or
a drilling jig that can handle pistols, such as Brownell’s SSR
Mounting System. Drill and tap for a 3-56 screw (or improve
this to a 5-40), and tighten it securely (as tight as possible
without snapping the screw). Be sure to use only a parallel-
blade hollow-ground driver that perfectly fits the screw head.
A sparing application of Loc-Tite or similar thread cement
will help ensure a lasting bond. Always trim off any part
of the screw that protrudes beneath the slide/top strap
undersurface.
You can adapt this same type of sight to Colt Government
models (and their clones) and other semiautos. This requires
inletting a shallow recess into the top of the slide so the base
FIGURE 16—Most adjustablerear handgun sights feature anelongated mounting tang fit-ted into an inletted slot at therear of the slide. A number ofmethods can secure the sightin place, and the most com-mon is probably with a screwthat extends down into theslide.
Gun Sights
will mount flush. Milling is certainly the faster way to accom-
plish this, but you can use a file so long as you carefully
center the work on the slide. Begin the cutting just behind
the ejection port and just wide enough to snugly accept the
base. You must cut a step (by milling or with hacksaw and
file) into the upper rear corner of the slide to accommodate
the sight body. A similar step is necessary for installation on
certain revolvers and you must position it very carefully. If
it’s too far forward, it can undermine the strength of the top
strap/recoil shield joint. Too far back and it can interfere
with hammer fall, which at times may require reshaping of
the hammer spur.
You install popular ribs like the Bo-Mar series, with specific
models to fit everything from Colt and Browning autos to S&W
and Ruger revolvers, by accessing existing dovetails. On this
type of job, you need to remove the factory sights, both front
and rear; then, grind off the front blade if it’s an integral
forging. File-fit the rib’s mount dovetail into the slot, taking
care to see that bearing surfaces are in full contact with
lampblack or chalk. With the rib in place, center-punch the
slide or top strap through the rib’s pre-drilled screw holes.
At this point, with the rib still in place, check to see that its
lower contour matches the curvature of the slide or revolver’s
top strap and barrel. If the correct rib fits the particular gun,
it won’t require more than a couple passes with a file here
and there for precise mating. Also check to see that the clear-
ance around the ejection port of an auto loader is sufficient.
If the fit checks out satisfactorily, remove the rib. Then, drill
and tap as previously described. To install, reposition the rib,
then Loc-Tite and tighten the screws (very tight!). Also, stake
the dovetail mount with a punch or (before inserting the
screws) silver solder the dovetail, the bearing surface under
the front sight, or even each pillar on a vent rib when recoil
is especially fierce.
Shotgun Beads
Shotgun beads function in a way that’s unique among all
gun sights. Unlike those found on rifles and pistols, they’re
not intended for any kind of precise aiming. Even when
shooting a gun with more than one bead, there’s no more
34
Gun Sights 35
than a cursory need for alignment. A bead simply signals the
position of the muzzle, without diverting the shooter’s atten-
tion from the target. It serves only as a mid-point reference
in a fluid, reflexive sighting reaction that originates at the
eye and ends with the target. There’s no focusing on the
bead as there is on a front sight; the focus must always be
on the target.
Practically all contemporary shotguns come with a bead at
the muzzle, and a few even provide a second, mid-barrel
bead. It’s the consensus of today’s shotgunners that a bead
helps them get on the target faster, helps determine leads
more clearly, and therefore produces more hits and bagged
game. It’s also true, however, that among all types of gun
sights, shotgun beads are the least critical. This is clearly
seen in the historical use of such beads.
Early Beads on Smoothbores and Flintlocks
Some of the earliest smoothbores, guns dating from 1500s
and 1600s, had small, barleycorn-shaped beads at the muz-
zle. This may lead you to believe that the “shotgun” bead is a
rather old development, but that’s not exactly the case. You
must keep in mind that the traditional smoothbore muskets
most likely shot a single round-ball slug. However, some
shooters observed that they were more effective-at least on
close targets-firing loads made of several smaller projectiles
(buckshot).
Flintlock fowling pieces, long-barreled, large-bore guns that
were the predecessors of true shotguns, were frequently fitted
with a bead or even a low blade. It’s not clear whether this
was a carryover from musket design or if the shooters recog-
nized a need to keep track of muzzles that extended three or
four feet from the eye. But it’s curious that when barrels
were shortened to more conventional lengths on the finer
flintlock shotguns of the early 1800s, beads were few and
ar between.
Throughout the 1800s and into the twentieth century, the
inclusion of beads on shotgun barrels was, at most, occa-
sional. Some guns had them, but many others didn’t. A
prominent rib between side-by-side barrels was often the only
concession to sighting. Where beads really began showing up
Gun Sights
with frequency was on the single-barrel guns (both single-
shots and repeaters) of the early 1900s. Here one can see
muzzle-mounted beads made of brass, ivory, steel (blued
or bright), and eventually plastic. Before long, such beads
became commonplace on side-by-side and over-under ribs
as well. In shape and position, these beads were markedly
similar to those found on the historic muskets. Interestingly,
they remain virtually the same today.
Beads for Today’s Shotguns
While beads remain fundamentally the same as those seen
centuries ago, there’s a healthy selection available for today’s
shotgunners. The choices hinge on three basic variables: color,
head diameter, and shank size/thread. The shooter will also
have to decide if he or she prefers relatively unbreakable
solid metal to more fragile but also more visible enameled or
plastic beads.
The usual colors are white, gold, and orange/red. The blued
steel beads so often supplied by gun makers are rarely cho-
sen for an add-on piece since they’re nowhere near as visible
as the brighter colors. White/ivory beads are either plastic or
enameled, or if solid metal, shaped from bright stainless steel
or aluminum. Gold beads are nearly always brass, but some
may be steel coated with gold-colored enamel. Red/orange
beads almost always contain plastic.
The beads, or globes, can range from .070 inch to .175 inch.
and the smallest sizes are used as a rear bead. The position
of the smallest sizes is normally midway along the rib. The
size one selects for a gun is strictly a matter of personal pref-
erence, since the bead should only act as a reference and
must never draw attention away from the target.
Shank lengths and thread sizes vary somewhat and when
you replace a broken or existing bead, it’s best to stick with
the same size unless the threads have damage. Shanks come
as short as inch and as long as inch. The desired length
will depend on the height of the rib, when present, and barrel
thickness. When the bead is to sit directly on the barrel, a
shorter shank will be in order. Common thread sizes for bead
shanks are 3-56 and 6-48, though Brownells also offers a
number with an 8-40 thread. Additionally, other makers offer
such sizes as 5-40, 6-40, and .146-48 (oversized 6).
36
Gun Sights 37
We should also point out that some manufacturers, Lyman
and Marble among them, offer beads with tapered, unthreaded
shanks driven into place. Also adding variety to the market is
Poly-Choke with a number of arrangements where the bead
is partially enclosed in a compact metal housing. These can
appear as a short cylinder with a rear-facing “lens” or as a
very abbreviated sloping ramp with the bead inset at the
angle of the face and top.
Installing Beads
The majority of bead installations will be screw-in types on
ribbed barrels (Figure 17). If you’re replacing an existing
bead, begin by removing it with a special tool made just for
this purpose. These sight installers have circular jaws that
won’t mar the bead surface even while gripping it very tightly.
(Brownells sells these in three different sizes to match bead
diameters.) Alternately, some beads feature a shoulder that
you can turn with a small wrench (Figure 18).
Beads that won’t screw out with the sight installer you can
cut off flush with a jeweler’s saw. Then, you drill out the
shank left behind and tap the hole for the new installation.
FIGURE 17—Shotgun beads may betapered (left) or threaded (right).
FIGURE 18—A Brownell’s Sight Installer is invalu-able for attachment or removal of screw-on shotgunbeads. It comes in three sizes, with collapsing jawsthat grip the bead firmly without scratching it.
Secure the barrel in a padded vise on the drill press table
using a machinist’s level on the rib to ensure that it’s level.
Set the press to drill no lower than the bottom of the rib. Be
sure to select the correct drill size for the new bead’s thread,
and turn the tap in at least four threads. Using the sight
installer, test the fit, taking great care to start it straight. If
the bead doesn’t seat all the way down on the rib it may be
necessary to grind a little off the shank (again holding it
securely with the bead installer). Apply a drop or two of Loc-
Tite or similar thread cement, and screw the bead in tight.
For the drive-in types, you ream the holes before driving the
beads into place. You can make a jig for this job from a piece
of soft scrap wood in which there’s a hole just smaller than
the bead. Hold the bead in the jig indentation and seat the
bead with a few raps from a light mallet.
You can also install beads on barrels lacking ribs, although
such guns are in the minority today. Such jobs will require
drilling into the barrel. Level up the work with a Top Dead
Center tool, then drill and tap the hole. Run the bead in
snugly and mark the excess shank length, then remove it
and, with a jeweler’s saw, cut off that part that penetrates
the bore. With a file or a small grindstone in a Dremel tool,
gently hone the stud flush after final screw-in. Polish over
the joint and any filing marks with a polishing point or emery
paper (Figure 19).
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FIGURE 19—Shown on the right is a finished bead installation on a double-barrel shotgun. On the left is a cutawayview of the installed bead. (Photos courtesy of U.S. Repeating Arms)
Gun Sights 39
Self-Check 2
Fill in the blanks in the following statements.
1. _______ _______ aren’t meant to be carefully aligned on a moving target.
2. Originally, glow-in-the-dark sights were developed for _______ and _______ use.
3. When mounting a screw-in bead, it helps to use a _______-jawed sight installer.
4. Because they aid visibility in dim light, police and hunters have found it useful to outfittheir handgun sights with _______, _______, or _______.
5. The three basic variables of replacement shotgun beads are _______, _______, and_______.
6. Sight alignment is crucial to handgunners because the _____ sight radius magnifieserrors.
7. Low-profile _______ sights for semiautomatics cannot be simply screwed or soldered in place.
8. Top-quality rear pistol sights are adjustable for _______ and _______.
9. You can usually fashion the slot for a new front sight blade with a _______ and needlefiles.
10. The popular Patridge-style sight combines a _______ rear notch and a flat-sided post.
Check your answers with those on page 97.
SCOPES: A BETTER LOOK
Since World War II, no development in the shooting world
has been more important than the adoption of scope sights.
These gun-mounted telescopes have garnered near universal
acceptance for the simple reason that they help shooters
achieve greater accuracy-more targets hit, more game
bagged. The shooter achieves accuracy in a number of ways.
• The shooter can see the target better.
• The shooter can fine-tune his or her aim by picking out
a spot on the target, or a vital area on game.
• The sight rarely obscures the target.
• As modern scopes developed, sight picture acquisition
became faster to the point where many shooters can “get
on” the target or game animal faster than by aligning
iron sights.
As a result of scope sights, older shooters have had their
sporting years extended and hunters are vastly more efficient
in the critical dawn and dusk periods. Also, those who are
unable to spend a lot of time practicing find it somewhat
easier to develop marksmanship skill.
Scopes aren’t without drawbacks, however. They add weight
to the gun and even the improved current models can’t
always stand up to rough handling. When something goes
wrong “inside,” you can’t repair the scope at the range or in
the field. Unless you can employ an alternate sight, the gun
is effectively out of commission.
Fortunately for today’s hunters and shooters, the reputable
scopes on the market aren’t prone to failure if treated with
reasonable care.
History and Development
We’re not certain who first mounted a telescope on a rifle.
However, the first occurrence of a scoped rifle probably came
shortly after the seventeenth-century German astronomer,
Johannes Kepler, improved on earlier telescope concepts.
Gun Sights40
Gun Sights 41
Kepler managed to reproduce an image within the tube
rather than relaying it to a “focal point” somewhere behind
the rear lens.
Kepler’s innovation required changing the curvature of the
front or objective lens to bring light rays together at an inte-
rior focal point. The rear or ocular lens was ground to focus
on the image and thus relay it to the eye. Kepler’s efforts
resulted in a much truer image delivered by a glass of man-
ageable size. (In attempts to get the lenses to focus, early
telescopes were often yards long.) Even with Kepler’s
improvement, images were usually fuzzy and distorted,
and to the viewer they appeared upside-down. One can
only imagine how fragile and prone to fogging these telescopes
were, so it’s understandable why they weren’t exactly an
immediate hit with shooters.
The performance of scopes improved as optical discoveries
occurred. Compound lenses, fashioned from two affixed
pieces of glass with differing optical properties, greatly
reduced troubling distortion. It was found that an erector
lens, inserted inside the tube between the objective and ocu-
lar, would set the image back on its feet. By the early 1800s,
gunsmiths and glass makers teamed up to build workable
telescopic rifle sights. By mid-century, American target
shooters used scopes, and Civil War snipers put them to
effective, if limited, use.
Over the next 50 years, scope sights were being crafted in
various places, and their availability was fairly widespread.
However, the hunting and shooting public still didn’t rush to
embrace their development. These scopes, many of which
were nearly a yard long and built around heavy-gauge steel
tubes, could add three to five pounds to an already ponderous
Sharps or Springfield rifle.
The long tubes and their nineteenth-century lenses seemed
to trap more light than they transmitted. Shooters likened
looking through one to being deep in a tunnel. The glass was
quick to fog in bad weather, and obtaining and maintaining a
positive aiming zero was, at best, trying. Shooters still found
iron sights most reliable for fighting Indians, for hunting, and
for protecting a frontier homestead.
The turning point came about the turn of the century when
scope lengths shrunk to under a foot and a half. Though
they still lent themselves well to bright-light situations, this
new breed of scopes caught on with target shooters first,
and hunters to a lesser extent. American firearms firms
like Stevens and Winchester, along with the German optics
makers Zeiss and Hensoldt, began mass-producing the
instruments. Not coincidentally, this was the dawn of the bolt-
action rifle era, and these two technological breakthroughs
seem to have augmented each other’s development. With bolt
rifles, shooters achieved much more accuracy than was pre-
viously possible. To take advantage of it they needed better
sights, and scopes provided this higher level of precision.
Refinements in the 1930s made scope sights even more pop-
ular and versatile, and while many shooters remained skepti-
cal about their usefulness, scopes spread to rifle ranges and
hunting camps across North America. Continued down-sizing
spurred the introductions of models like the Lyman Alaskan
and Weaver 330. Such scopes were about a foot long, built
on slender 3/4 or 7/8 inch tubes, and came in relatively low
2.5X and 3X magnifications respectively. These lightweight
scopes had great appeal to hunters.
By the decade’s end, Zeiss had developed a process to treat
lens surfaces with a thin, transparent layer of fluoride or
magnesium oxide. This was a giant step toward eliminating
the traditional problem of light reflecting from the glass
rather than passing through it (Figure 20).
Coated lenses are far more efficient at transmitting the light
they take in, therefore conveying brighter, clearer images,
even at times of dim ambient light.
The years following World War II brought a series of further
refinements that finally won the shooting public’s favor. One
major refinement involved filling the tube with nitrogen gas
and sealing it airtight. This prevented fogging of the inner
lens surfaces when the shooter encountered temperature
extremes or wet, humid weather.
The early 1950s saw the advent of variable scopes that could
increase or decrease magnification power at the turn of a
ring. Shooters soon learned that scopes could be highly ver-
satile-at least with the resolution of the problems of reticle
Gun Sights42
Gun Sights 43
“growth,” inferior light-gathering and field of view, and zero
shifts. Current variables are nearly the equal of fixed-power
models in most regards. They’re perhaps a bit bulkier, but
they’re capable in more situations.
Reticle presentation then became upgraded. The aiming
marks, seen as crosshairs, posts, dots, and various other
combinations came to be made of fine wire or filament and
lines etched on glass. In years past, they looked like spider
webs. They come in various widths, arrangements, and
combinations, depending on the design (Figure 21).
FIGURE 20—The latest line of Carl Zeiss scopes, the Z-series, features the patented Zeiss T multicoating, whichevolved from Zeiss’ early work with lens coating. (Photo courtesy Carl Zeiss Optical, Inc., Petersburg, VA)
In most older scopes, the reticle was permanently fixed within
the tube. The only way to make a sighting adjustment was
to move the entire scope in its mount. Early scope users
considered an external adjustment superior (even though
it required a bulky, delicate mount) because it allowed the
scope’s construction to be simpler, stronger, and more
effectively waterproof (Figure 22).
A few older models featured reticle adjustment inside the
tube (usually just one), and the reticles tended to move off-
center in the field of view. Today’s models feature permanent-
ly centered reticles, easily adjusted by screw-in or dial mech-
anisms housed in the upraised turrets located midway along
the scope body. You would rarely see external adjustment
Gun Sights44
FIGURE 21—Here are the most common scope reticle styles (from left): crosshairs, post,duplex, and dot.
FIGURE 22—You’ll find exter-nal adjustment scope mountsonly on match rifles thesedays, as advancements inoptics technology have led to internal adjustments thatare both accurate and reliable.Nevertheless, competitorsremain loyal to large-knobbedmicrometer fixtures that movethe scope body from the outside.
Gun Sights 45
scopes any longer outside bulls-eye competition or on collec-
tor guns; and in the United States, only Unertl still makes
this type scope and mount. Instead, we now see multiple
crosshairs, range-finding scales, and battery power for illu-
mination in the dark.
After nearly 200 years of development, today’s scopes provide
tremendously effective sights for millions of shooters. They’re
strong, lightweight, and reliable, and by making the targets
appear larger, brighter, and sharper, they make us better
shooters and hunters.
Functions and Features of Rifle Scopes
The great demand for scopes by nearly all segments of the
hunting/ shooting world has spurred the evolution of a wide
range of highly specialized models. Today you can buy scopes
specifically designed for hunting anything from a rat to a
grizzly bear, for pinpointing tiny X-rings or distant steel sil-
houettes, or just for knocking tin cans off a fence post. There
are scope sights made for pistols and shotguns. There are
also others intended solely for air rifles, and amazing night
vision units (not widely available to the public) for military
and police sniper duty. Also available are infrared rifle scopes
for hunting that maximize light transmission in the red part
of the color spectrum.
By far, the most common scopes are hunting rifle scopes, but
even these come in a mind-boggling array of shapes, sizes,
power capabilities, and internal features. Most likely the con-
ditions of the hunt or competition or recreational pastime will
determine the appropriate model (Figure 23).
Hunting Scopes
Hunting scopes must go beyond simply presenting a clear,
magnified picture of the intended quarry. Big game hunters
can often benefit from the scope’s enhanced twilight capability,
a function achieved by employing a large-diameter objective
lens that takes in lots of light (Figure 24).
Gun Sights46
FIGURE 23—Pictured are Steiner’s revolutionary new color-discriminating rifle scopes. The Penetrator series maximize light transmission in the red part of the spectrum, reflect blue and green light back into the woods, and enhance the eye’s ability to spot game against a forest background. (Photo courtesy Steiner Optik through
Pioneer Marketing & Research, Inc., Westmont, NJ)
Gun Sights 47
Variables
Objective lens diameter isn’t the only element that con-
tributes to overall size. There are other dimensional factors to
consider when selecting a scope. Variables, because they
must accommodate shifting interior lenses, are nearly always
longer than similar fixed-power models. The wider the range
of power settings, the greater the length required. For exam-
ple, a 6-24X scope will be considerably longer than a 3-9X of
similar optical quality. The greater length also adds weight
and makes the scope more likely to snag on or bump against
brush.
An additional size consideration is the scope’s proportion to
the rifle. On a diminutive .22, a carbine, or one of the new
breed of down-sized “mountain” rifles, a massive, large-objec-
tive variable will disrupt the balance. This makes for a top-
heavy unit that comes to the shoulder clumsily and is slow
to access the target. Also, the looks of such a combo will be
just as awkward to many. Generally, a smaller-sized rifle will
handle and look better with an optic built on a similar scale.
FIGURE 24—Pictured is the Leupold 3 ö 9-50mm large objective variable scope that provides hunters with maxi-mum visibility during early morning and late evening hunts. Those who will be walking far or climbing mountainswill suffer, however, from the extra weight of a “wide-eyed” model. These users probably will want to compromisefor a more compact unit that combines reasonable twilight ability with a handy carrying weight. (Photo courtesy
Leupold & Stevens, Inc., Beaverton, OR)
Various Power Ratings and Their Uses
Perhaps the key factor for most scope purchasers is power
rating, an area where an enormous range exists. Today you
can find scopes ranging from 1X (no magnification) all the
way up to 40X (or greater in customized models). You must
understand that as power increases, field of view decreases.
For example, a typical 4X scope will deliver a 32 foot width
of field at 100 yards, while a 10X shows only 12 feet at that
distance. This varies somewhat with construction but not
greatly, and variables nearly always yield a smaller field at
the same power as fixed scopes.
Shooters who can genuinely use higher magnification scopes
are probably firing on stationary targets easily distinguished
from their background. This would include bulls-eye, silhou-
ette, and bench rest competition, varmint hunters, and to
some extent, stalking big game in open plains country.
For use on game that’s moving and/or in heavily wooded or
brushy areas, a high-powered optic with its very limited field
of view frustrates hunters’ ability to engage and hold on their
target.
For hunting most North American big game-deer, elk, black
bear, and moose-big game hunters have settled on 4X as the
consensus setting. Today, the 3-9X variable also enjoys great
popularity. Such scopes offer a good field of view, are normally
fitted with a 32mm or larger objective for optimum light gath-
ering, yet aren’t overly large, weighing anywhere from 10 to 15
ounces. At 4X, deer-sized or larger game is sufficiently mag-
nified for the shooter to attain lethal shot placement at the
practical limit of his or her ability to shoot accurately-out to
300-400 yards.
Many professional guides opt for iron sights on their “stop-
ping” rifles when hunting grizzly bears and dangerous game
in Africa. Their scopes are usually at the low end of the
power curve, 1X to 3X, as field of view and speed become
more important than increased magnification. Objective lens
sizes are also scaled down on such scopes, since the hunters
prefer economy weight (under 10 ounces) and maneuverabili-
ty to twilight capability. We should make clear here that
objective lens dimension has nothing to do with field of view.
Gun Sights48
Gun Sights 49
Rather, the ocular lens governs the visible field. Generally,
lenses that yield wider fields require diminished eye relief
(the distance from the rear lens to the eye), so a compromise
must be made here to make the scope functional.
Hunters can use higher-power scopes like 6X to 12X to great
advantage for open-country game like pronghorn and cari-
bou. Here, long shots are the rule and the hunter can often
take the time to get in a steady shooting position. Objectives
tend to be big on such scopes (40mm or more). However, if
the hunt involves much walking, the 12 to 20 ounces they
can add may prove burdensome, and again, the user is bet-
ter off with a smaller model.
Those who climb for bighorn sheep and mountain goats,
usually found in fairly open places where a close approach is
unlikely and shots tend to be long, also need the smaller
model. Reaching sheep and goats is such an arduous ordeal,
however, that hunters look for any possible way to lighten
their loads. Sheep and goat hunters often rely on 3X to 6X
scopes or smaller variables with mid-size objectives. Ideal
for such hunting (and also finding favor for use on antlered
animals) is a new class of low-end variables, a 1.5-6X, 2-7X,
and 2.5-8X category. They offer surprisingly good definition
and light-gathering ability despite streamlined objectives that
may measure no more than 20-28mm.
Among hunters, varmint hunters are most likely to use heavy
powerhouse scopes. These formidable optics often range up
to 20X or 24X, and at times exceed 30X, although, at that
magnification, the mirage of heated air rising from the
ground can be thoroughly distracting. Needless to say, the
quality models offer tremendous magnification. The magnifi-
cation makes it possible for a flat-shooting, heavy-barreled
varmint rifle to hit a tiny target as far as a quarter mile
away. Weight isn’t such an important factor here since the
sport typically involves very little walking and the shooters
fire from a rest or otherwise supported position.
Varmint scopes are likely to boast huge objective lenses,
from 40 to more than 50mm. This isn’t because the users are
expecting to encounter game at the very beginning and end
of the day in the manner of deer hunters. Rather, the higher
power requires a greater amount of light to transmit a high
degree of clarity and resolution. Related to this is the peren-
nial question concerning the optimum power setting in low
light. Many shooters believe that lower powers are superior at
these times because they do a better job of transmitting light.
However, higher magnifications are actually better at aiding
visibility simply because they bring the image closer. Compared
to what one sees with the naked eye at 150 yards, an image
at 4X appears to be inside 40 yards. But at 8X that same
subject looks as if it’s just 20 yards away (Figure 25).
Another feature found on most varmint scopes that may be
missing from other hunting models is parallax correction.
Parallax is an image transmission condition that can lead
to sighting errors when the focal point doesn’t coincide with
the plane occupied by the reticle. That is, the image projects
ahead of or behind the reticle. You can notice this condition
when the subject seems to “float” over the reticle as the
user’s head shifts. When parallax isn’t present, the image
and reticle move together. Parallax becomes pronounced only
on very close images, say inside 50 yards, and at that range
the sighting error is insignificant on all but the smallest tar-
gets. Beyond 150 yards, very little parallax will be evident.
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FIGURE 25—Shown is the Leupold 3.5 �� 10 adjustable objective varmint scope. Its distinguishing feature is aunique elevation adjustment system borrowed from Leupold’s legendary bench rest scopes. The shooter can makeadjustments in 1/4 minute intervals, enabling him or her to “pinpoint” shot placement, which is what varminthunting is all about. (Photo courtesy of Leupold & Stevens, Inc., Beaverton, OR)
Gun Sights 51
Most modern scopes are manufactured to be free of parallax
at 150 yards. Because some varmints present such minus-
cule targets and because parallax is much more noticeable at
higher powers, manufacturers have outfitted certain scopes
with adjustable objective lenses. These lenses simply rotate
one way or another according to marked gradations to cor-
rect for a particular distance. Most target scopes will also
have this feature, as do certain lower-power models more
typically suited for big game hunting. The parallax correction
may not have much practical application on these, but it
does offer a bonus for shooters concerned with ultimate
accuracy. For serious varmint hunters, however, parallax
correction can produce tangible results in the field (Figure 26).
Hunters of small game like squirrels and rabbits, as well as
plinkers, can usually satisfy their needs with small (4 to 8
ounces) low-magnification scopes. These are often built on3/4 inch tubes, housing objective lenses with 15 to 24mm
diameters, and they rarely exceed 4X. Intended for .22 rimfire
rifles, these low-end scopes provide adequate magnification
and light-gathering ability for the short ranges over which
the guns are effective.
FIGURE 26—Parallax is a condition that occurs in optical sighting instruments when the image is transmittedbehind (middle figure) or in front of (lower) the reticle. Error-free sighting occurs only when the scope is free ofparallax (top), though the degree is usually insignificant unless targets are quite small, in which case the shooterwould use a higher-powered scope.
Target shooters need not consider quite so many variables
when it comes to selecting a scope. When the emphasis is on
precision, and shooters line up their shots with painstaking
effort (as is the norm in most competitive shooting) magnifi-
cation is a vital factor. Therefore, bench rest, bulls-eye, and
silhouette match shooters want and can use plenty of power
without suffering from the resulting weight and narrow field
of view. 15X is about the minimum commonly employed by
experienced marksmen and it’s not unusual for top competi-
tors to resort to scopes topping 30X and even 40X.
We should note that everyone can’t use such extreme powers
effectively. While it’s true that the target will appear much
larger, it’s also true that the shooter’s movements are equally
magnified. Unless the shooter fires the rifle from a supported
position, as is the case in prone or bench rest events, it will
seem that the target is “dancing” across the field of view. It
takes a skilled rifleman with supreme powers of concentration
to steady this sight picture and make a good shot. The lack
of time to accomplish this is another reason why big game
hunters are unable to benefit from ultrahigh-power optics.
Quick and precise sighting adjustments are also important
to competitors. Because subtle shifts in the wind can cost
points, shooters must be able to make instant corrections.
On scopes designed for silhouette and bench rest shooting,
high-profile adjustment knobs shift the cross-hairs slightly
with each readily felt “click” (normally inch at 100 yards).
Silhouette shooters also use this system when moving from
one target distance to another, dialing a predetermined num-
ber of clicks to alter points of impact.
In bulls-eye shooting, shooters encounter the last vestiges
of external adjustment in the form of micrometer-style rear
mounts. Supporting 20X to 25X, long-tube scopes with fixed
reticles, these precision mounts contain spring-loaded stabi-
lizers that press opposite the two graduated micrometer
heads, one for elevation, the other for windage. As with scope
turret knobs, they work with audible and felt clicks. There are
usually 50 clicks per revolution of the head and the distance
each click shifts the point of aim depends on the measurement
between the front and rear bases. The closer the mounts, the
greater the adjustment. Smallbore rifle shooters, who typically
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Gun Sights 53
want 1/4 inch clicks at 50 yards, accordingly will space front
and rear mounts 7.2 inches apart.
Pistol, Shotgun, and Air Gun Scopes
Though some once considered it odd, it’s no longer unusual
to see a scope mounted on a pistol, shotgun, or air gun.
Recent scope designs and materials have made it possible
to attach a scope to virtually any type firearm.
Pistol Scopes
Pistol (or handgun) scopes emerged as a major development
of the 1980s with models tailored specifically for hunting and
competition, for revolvers, semiautomatics, and single-shot
guns. When employed by skillful handgun shooters, they
yield the same benefits enjoyed by rifle shooters for so many
years.
The obvious restrictions on size/weight (7 to 10 inches and
about 8 ounces is average) and the pistol’s relatively short
effective range have limited useful features, however. Low
magnification (typically 1X to 4X and rarely topping 6X),
compact dimensions, and moderate light-gathering capabili-
ties characterize today’s pistol scopes. In addition, eye relief
is a critical factor. For many years this was also the case
with rifle scopes. The shooter had to hold his or her head
rigidly in just the right position to see the full field of view.
The tendency was to creep forward on the stock and end up
with a half-moon cut on the forehead from recoil (Figure 27).
Design advancements have given shooters a couple inches
leeway in obtaining proper eye relief, an especially important
concern of hunters who must get “into” the scope
and “on” their targets in a hurry. And in certain
cases shooters will also opt for long eye relief, when
fierce magnum recoil is present or on rifles where
the scope is mounted in a forward position.
FIGURE 27—Eye relief is the distance between the scopeocular (rear) lens and the shooter’s eye. You mustaccount for eye relief when mounting the scope. Eye relief varies from one individual to another, so the shootershould be on hand for measurement.
Eye relief for a pistol scope user is a more demanding propo-
sition since shooters hold handguns some distance away
from their head and because there’s no cheekpiece to estab-
lish a natural line of sight. Pistol scopes are built so that the
correct eye relief will appear about 10 to 20 inches behind
the ocular lens. It takes a good deal of experience to be able
to routinely assume and maintain this position (Figure 28).
Hunters and silhouette shooters will generally opt for more
powerful 3X and 4X models with larger objective lenses
(though normally not larger than 32mm). Bulls-eye and
practical competitors who perform in rapid-fire events
that demand speed tend to stick to lower 1X, 2X, and 3X
magnifications.
Electronic optics are also quite popular with match shooters,
particularly among bulls-eye competitors. These units operate
on small batteries and project an illuminated dot onto the
field of view (Figure 29).
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FIGURE 28—Handgun scopesprovide extended eye relief,that is, greater distancebetween the eye and rear lenswhile still providing a full fieldof view. Lower magnifications,like 1.5X to 3X, are the mostpopular, but higher powers areavailable.
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The dot acts as a reticle and you can adjust the width and
intensity by turning a switch. Electronic optics caught on big
in the early 1980s because they’re fast to acquire the target
and offer a somewhat simplified sighting procedure. More
importantly, they have prolonged the competitive careers of
many older shooters who began to have trouble focusing on
their front sights. Originally, electronic optics were without
magnification, but recently we’ve seen the production of 2X
and 3X models. Handgun hunters haven’t been so quick to
adopt the electronics, probably due to the electronics’ bulk
and lack of useful magnification. On rare occasions a shooter
may want an electronic sight mounted on a rifle or shotgun
(Figure 30).
FIGURE 29—The Aimpoint5000 is a 30mm electronicred dot optical sight that runson lithium batteries. The mainunit, designed for all types ofpistols and revolvers, meas-ures 5.5 inches. It’s not nec-essary to focus or center thedot. The shooter simply putsthe dot on the target andshoots. (Photo courtesy of
Aimpoint, Herndon, VA)
FIGURE 30—The compactlightweight Laserdot utilizes astate-of-the-art laser diodethat eliminates all movingparts and tubes, which werenecessary in earlier designedlasers. This allows theLaserdot to withstand heavyrecoil and demanding shootingconditions. Laserdot mountseasily into standard one inchrings, or with its optional railmount for use on pistols,rifles, shotguns, air rifles,and bows. (Photo courtesy of
Aimpoint, Herndon, VA)
Shotgun Scopes
Just as handgun optics became quite common in the preced-
ing decade, scopes for both regular shotguns and those
bearing slug barrels will become widespread in the 1990s.
Fast-developing areas restrict rifle use for deer hunting. So
more and more hunters will have to turn to shotguns if they
want to continue the sport (Figure 31).
Shooters have experimented with shotgun scopes (often suc-
cessfully) for many years, but recent improvements in slug
barrels and slugs made these guns accurate enough to bene-
fit from precision sights. The majority of shotgun scopes on
the market are lightweight, low-magnification models of 4X
or less with objectives around the standard 32mm. Expect to
see this category grow over the next several years (Figure 32).
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FIGURE 31-The Leupold 1 �� 4 shotgun scope is just one in a line being designed specifically for shotgun hunters.Leupold shotgun scopes are parallax-adjusted to deliver precise focusing at 75 yards, as opposed to the 150yards, which is typical of rifle scopes. (Photo courtesy Leupold & Stevens, Inc., Beaverton, OR)
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Air Gun Scopes
Scopes that carved out a steady market niche are those
designed specifically for air guns. Along with the development
of pellet rifles and pistols powerful enough to kill pests and
small game came the demand for suitable optics. At first
some felt that air gun scopes would work well on any small
firearms model, but they did not hold up on hard-recoiling
spring-piston guns. Lenses would crack, reticles would shake
loose from their moorings, and internal adjustment mecha-
nisms would go haywire.
The problem was caused by the way these scopes were
designed to withstand the rearward thrust of firearms recoil.
The spring-piston gun acts in exactly the opposite manner,
kicking forward when the piston slams against the front of
its cylinder.
Air arms manufacturers and importers soon introduced
scopes with lenses braced to withstand forward recoil and
enthusiasts rushed to put them on their guns.
Air gun scopes have been modest in size and power, commonly
4X with 32mm or smaller objectives. However, a number of
variables up to 3-9X and 4-12X with 40 to 50mm objectives
have also been on the market. A feature many of them have
included is manual parallax correction, necessary for the
close ranges and tiny targets. Air gun silhouette and field
target events are growing sports, but recent technology in
compressed air power has led to light-recoiling guns that
don’t need specially braced optics. Also, many higher-quality
firearms scopes already have the rigid construction to stand
up to spring-piston recoil.
FIGURE 32—In 1989, Remington introduced a complete rifled slug accuracy system for its 12 gauge Model 11-87semiautomatic and Model 870 pump-action Deer Guns. They feature a permanent, integral scope mount on thebarrel and a new, interchangeable, rifled “Rem choke” tube. They also have a permanently attached cantileverscope mount, including rings, that extends back over the receiver to provide normal eye relief with rifle scopes.(Photo courtesy Remington Arms Company, Wilmington, DE)
Reticles
When deciding which scope to buy, the purchaser must also
consider the type of reticle that suits his/her needs. As previ-
ously mentioned, they come in three categories: crosshairs,
posts, and dots. Within each category there’s a mind-boggling
number of variations.
Crosshairs
Fine crosshairs are excellent for precise accuracy but they
can be difficult to see in poor light. Bulls-eye target competi-
tors who have the time to “find” them and some varmint
hunters favor them.
Posts
Posts are especially popular in Europe where they originated.
They come in single (one vertical from the bottom), three-post
(from the bottom and sides), and four-post (all four directions)
versions, usually ending in a point. They don’t meet, therefore
leaving a clear area in the center of the field of view. Post ret-
icles are easy to see and don’t obscure the target, but don’t
facilitate finely tuned aiming. They’re very useful for big game
at close ranges.
Duplex
A combination of the post and crosshair styles is the duplex
reticle. The duplex’s “legs” begin as thick posts, then taper
abruptly to narrow crosshairs at the center. Frequently they
are without a top post. The solid posts provide an easily
accessed reference and the thin central hairs allow fine preci-
sion, so long as the light is sufficient to see them. Even when
conditions are rather dark, the post arrangement makes it
possible to use the scope with satisfactory results. Duplexes
are probably the most versatile reticles, and are quite popular
among U.S. big game hunters.
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Dots
Dot reticles lend themselves well to the specialized uses of
match and varmint shooting. In such uses the shooter has the
time to pick up a circular point small enough to provide exact
aiming without obscuring the target. Top competitors often
find it easier to concentrate on a dot during lengthy events,
especially in the standing position when the pronounced
movement of crosshairs can be a nagging distraction.
Bulls-eye shooters use one-minute-of-angle dots that match
the size of their X-rings, whereas bench rest shooters want
pinpoints as tiny as one-eighth minute. Varmint hunters
sometimes experiment with multiple dots on a vertical axis.
Installed by custom scopesmiths, they show point-blank
holds for various ranges with a given load, or are made
in different sizes to indicate range on a certain animal.
Obviously, it takes a knowledgeable, accomplished shooter
to realize their potential.
At the risk of digression, it is important to note that you can
make range estimates by using a system of parallel horizon-
tal crosswires designed to bracket a certain measurement at
a specified distance. Often this measurement is 18 inches, the
nominal depth of a mature deer’s chest. The user determines
the distance to the animal by trying the various brackets,
then uses the appropriate crosswire for the hold. This takes
time, of course, and at the moment of truth such systems
with their numerous wires often prove confusing. Not many
big game hunters opt for such range-finding scopes.
Mounting a New Scope
Although mounting a scope on a rifle isn’t a difficult gun-
smithing task, you must do it correctly for the rifle to perform
to any standard of accuracy and consistency. A gun with a
crooked, loose, or otherwise improperly mounted scope sight
simply won’t shoot straight. For that reason, many gun owners
prefer to have a professional accomplish this important task,
relying on his/her expertise to get it done right-regardless of
the added expense.
For the gunsmith, scope mounting is a measure of profes-
sional service that involves customer relations as much as
technical know-how. The amount of time it takes to install
a scope on most modern hunting rifles is minimal, since
they’ve been manufactured with the presumption that a
scope will eventually be mounted. Older guns, military
weapons, and certain target models may pose more of a
challenge, although mounting hardware is commercially
available for practically any modern mass-produced firearm.
A professional scope-mounting job should be a confidence
builder for the customer. It is the finishing touch on any
gunsmithing operation that requires disassembly of the gun,
the cap to the purchase of a new firearm, or perhaps new
“eyes” for an old friend. With the scope properly mounted,
the shooter heads to the range fully confident in his/her
equipment.
Mount Components
Mounting a scope on a gun requires using hardware made
specifically for that gun. Hardware usually includes mount
bases (or blocks) and rings (Figure 33).
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FIGURE 33—Leupold’s basesand rings are now available inmatte (sheenless) finish.(Photo courtesy Leupold &
Stevens, Inc., Beaverton, OR)
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You’ll find some of the hardware fashioned as one-piece
combination base/rings. In some cases, the firearm will have
parallel dovetail grooves machined into the top of its receiver,
and these you can use for attaching simple clamp-type rings.
Rifle Mounts
On nearly all rifles, mount bases join directly to the receiver
or side plate with screws. This is a straightforward job on
most guns since they come from the factory with screw holes
already tapped. There are a number of manufacturers offering
quality mounts tailored for an extensive selection of modern
rifles, and it’s not difficult to find mounts for many older
models. Many such bases are sold in kits containing the
correct screws.
The rings hold the scope. These come in 3/4, 7/8, and 1 inch
sizes, as well as metric 26 and 30mm diameters. One inch
rings are by far the most prevalent. Most rings consist of
mated semicircles that detach to accept the scope, then re-
attach with screws. Formerly, rings were also circular bands
that cinched tight at an overlapping union. These were fine
for accommodating straight-tube scopes (those lacking flared
ocular and objective bells) but bending them wide enough to
fit around the tube sometimes caused them to crease or to
scratch the scope. You’ll find split rings used in almost all of
the current mount offerings.
Rings attach to mount bases in several ways as follows.
• Some clamp to the mount’s rail or rib-like features
• Others hold onto a slot with a spreading claw
• Another type fits over a protruding stud and is held in
place by friction or with a set screw
• Still others screw directly to holes threaded in the base
All of these methods have proven effective so long as the
device is well made of quality materials, but logic suggests
that the simplest design with the fewest parts will be the
strongest.
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Mount bases and rings were originally made of steel and
most still are. However, aluminum mounting hardware is
catching on quickly as a lightweight alternative, and in most
cases is proving sufficiently durable.
Among the numerous scope mounts introduced over the
years, a handful stand out as enduring and popular. The
best ones have proven durable, easy to install, fairly light-
weight, and able to maintain the scope’s zero when refitted
after removal. You can scope virtually any rifle from the
smokeless powder era except for certain later military arms.
One of the most popular types of “top” mounts-so-called for
its position on top of the receiver or barrel-is the dovetail
style. Generally, dovetail mounts come as rails that attach to
the receiver with screws, or on small-caliber rifles, grooves
milled into the receiver. The rail, which comes in both one-
and two-piece configurations, is beveled top to bottom to mate
with corresponding clamping “jaws” on the rings’ riser piece.
Most frequently the dovetail rail screws into tapped holes on
the top of the receiver, particularly on a bolt-action rifle.
You’ll often find a side plate mount used in the case of lever-
actions like the Model 94 Winchester, where the rear of the
receiver pivots back to open the breech. As the name sug-
gests, the side plate style of mount fastens onto the receiver
wall via screw or pin holes. The plate extends upward along
the receiver to suspend the scope above the bore axis, either
angling into position directly over the top of it, or holding it
out to one side (diagonally to the bore) on top-ejecting actions
such as the older Model 94s. Many side plate mounts also
incorporate some type of dovetail grooves, thereby enabling
use of the most common-type ring.
Around 1950, the W. R. Weaver scope company of El Paso,
TX, introduced what has probably been the top-selling mount
of all time. The Weaver top mount is a dovetail rail improved
by a perpendicular slot that engages long ring-clamping
screws. The design acts as a recoil lug for the scope and it
provides a much greater bearing surface than the clamp ears
alone. Weaver-type mounts fit a long list of rifle models and
many manufacturers offer rings to fit it. The Weaver-type
mount has gone through minor changes (notably in the
clamping screw) but this proven mount remains a favorite of
American shooters and currently fits hundreds of rifles.
62
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Another old favorite is the Redfield-style mount, still made by
that company and many others. It’s available in one- or two-
piece versions, the bases secure the front and rear rings in
different ways. The front ring has a circular, dovetailed stud
on the bottom, which you insert into the base, then turn to
lock in place as it snugs against the oblong base slot. The
rear ring is snugged by countersunk screws on either side.
The Redfield type and similar designs make scope removal
quite fast, as it’s only a matter of loosening the rear ring,
then pivoting the works free of the front base (Figure 34).
Many big game hunters favor quick-detachable scope mounts
though they’re the most expensive on the market. Such
mounts facilitate rapid scope removal/replacement with rings
featuring lever or claw-like fixtures that clamp onto the base
with simple hand manipulation. Many, though not all, of the
quick-detachables are European made. Their built-in clamp-
ing mechanism boosts their price.
Pistol Mounts
Pistol mounts function much the same as those for rifles,
at least in the case of revolvers and single-shots, where the
bases respectively fasten onto the top strap or barreled
action. Most handgun mounts can utilize adjustable sight
screw holes. If they’re not present, you must drill the holes
accordingly. Also, there are quite a few “no-gunsmithing”
versions that clamp onto the top strap or another part of
the frame in addition to using any existing screw holes.
FIGURE 34—The Redfieldbridge-type mount has beenaround for more than 50 yearsand is still going strong. Itspopularity is in part due to itseasy-off/easy-on again capa-bility. This is made possible by turning the rotary dovetailstud on the front ring into asnug friction fit in an oblongslot on the base.
There may also be a ring-like brace that clamps directly
around the barrel for installing the mount on a hard-recoiling
magnum revolver. These guns often have three rings to
secure the scope in the wake of the violent recoil. Generally,
“no-gunsmithing” mounts simplify the installation job, but
also add significant bulk to the gun.
Scope mounts for a semiautomatic pistol are often more elab-
orate than on a revolver since the slide must remain free to
move back and forth. Again, frame-clamping versions are
available, but many shooters who want to scope self-loaders
choose grip mounts. These have a long extension that angles
down on the side opposite the ejection port and replaces the
factory grip. Accordingly, this portion of the mount is shaped,
checkered, and/or finished to match the standard grip. It
features screw holes that line up with those in the frame,
making for a handy installation job (Figure 35).
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FIGURE 35—The “Guide-Line” handgun scope mounts from Williams eliminate installation problems often encoun-tered when installing a scope on a handgun. They install easily with no required drilling or tapping. (Courtesy
Williams Gun Sight Company, Davison, MI)
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Slug Shotgun Mounts
Many of the latest slug shotguns are factory drilled and tapped
to accept top mounts just like a rifle, but most existing slug
bores must be customized for this purpose. Additionally,
there are side mounts expressly made for certain models;
some require gunsmithing, some attach by replacing factory
trigger pins with long mount bolts, and others simply clamp
to the receiver. Redfield makes a mount that clamps onto the
rib, making it possible to scope side-by-sides and over-unders
as well as the more customary pumps and semiautos.
Scope Installation
There was a time when the most difficult part of mounting
a new scope was correctly aligning it with the gun’s bore.
This required a professional gunsmith (or at the very least a
knowledgeable enthusiast) using try squares or a drilling jig
to determine true mount placement. Today the guns come
drilled and tapped from the factory, which all but eliminates
the preliminary step. Even if they weren’t, or in those rare
instances where the screw holes aren’t true, modern scopes
have a much greater capacity for adjustment than their pred-
ecessors-certainly enough to compensate for minor misalign-
ment. When you can see misalignment, however, you should
return the gun to the dealer or manufacturer. In instances
where you can’t return the gun, it may be necessary to drill
new mount screw holes. Then it will again be crucial to
achieve proper alignment with the bore.
For the majority of scope-mounting jobs today, the first step
is to thoroughly cleaning any grease or oil from the gun,
mount, screws, and the scope itself. Residual lubricant on
any of these parts can lead to future slippage. Even the
slightest movement can undermine accuracy, causing the
scope to shift within the rings, perhaps damaging the tube
or adjustment turrets. Even worse, recoil applied to a loose
mount can sometimes shear off screws, and the entire works
may jerk free of the gun.
Wiping with a clean cloth will probably do, but to ensure
clean mounting, you should use a fast-drying solvent or
degreaser. Don’t forget to include screw threads and screw
holes, which you can access with cotton swabs (Figure 36).
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Attaching the Mount
With the gun and mount hardware free of grease and oil, it’s
time to pull out the tools. You don’t need much when utiliz-
ing predrilled screw holes: the correct screwdrivers or Allen
wrenches, a small mallet, and a tube of Loc-Tite or similar
thread cement (Figure 37). Using the right screwdriver is an
absolute must. To tighten the screws sufficiently without
jumping, the driver must fit perfectly in the screw head slot.
It must have a hollow-ground blade with parallel sides, and
the blade should be long and thick enough to fully engage
the slot. When you don’t have the correct size at hand, grind
one to fit the screw. Improperly fitting driver blades are
bound to jump from the slot, and the damage they do is all
too clear. Damage such as mangled screw heads that may be
next to impossible to remove, scratched rings or mounts or
barrel finish, and gouged stocks. These are immediate and
unmistakable signs of amateurish scope installation.
Some mounts use Allen screws. Naturally, these are easier to
work with as long as the head is heavy enough to take the
necessary pressure involved in tightening. Some 6-48 (stan-
dard sight-mount screw size) Allen heads are rather dainty,
so if the least bit of rounding occurs, back the screw out and
start over with a fresh one.
66
FIGURE 36—Thoroughly cleanand degrease gun and mountsurfaces before beginning anyscope installation. Even theslightest bit of give, magnifiedunder recoil, can lead to aloose mount and in extremecases can result in screwsshearing off.
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Keep in mind that scope mount screws must be very tight.
It’s possible for a strong-armed gunsmith to twist off a 6-48
screw, but with even, judicious pressure, this should not
happen. Another way to achieve an extra degree of tightness
is to rap smartly on the screwdriver handle with the mallet
as you make the last turn. This can often account for anoth-
er quarter turn without compromising the screw’s strength.
For especially hard-recoiling magnums and on very light
“mountain” rifles, it may be wise to substitute heavier 8-40
screws, a measure some manufacturers already provide on
certain current pump, lever, and auto rifles. This of course
means retapping the base and receiver screw holes.
Double-check to make sure the base(s) is correct for the gun.
Position the bases and start the screws until they’re snug
but not tight. Then, alternating between each screw, finish
the tightening job, taking up a half, then a quarter, turn at a
time until there’s no more looseness. It’s a good idea to coat
the screw threads with a drop or two of Loc-Tite to guard
against loosening.
Caution: Use Loc-Tite and similar metal adhesives sparingly,
however, since it may be necessary to break the bond some-
day. Also, any excess could seep down into the receiver and
freeze or otherwise interfere with moving parts.
FIGURE 37—The fundamentaltool needed for nearly all sightmounting jobs is a top-qualityscrewdriver. The screwdriver(s)should have hollow-ground, flat-sided blades that completely fillthe screw head slot. Allenheads should contain hardenedsteel to avoid “rounding off” as the screw tightens.
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Self-Check 3
Indicate whether the following statements are True or False.
_____ 1. Coated lenses and tubes sealed with nitrogen gas are two of the major factors inscope development.
_____ 2. Handgun scopes must offer extended eye relief.
_____ 3. Top mounts, like the popular Weaver series, generally attach to the top of thereceiver or barrel with screws.
_____ 4. The first thing to do when shots fail to form a group during sighting-in is to checkthat mount, ring, and action screws are tight.
_____ 5. “No-gunsmithing” pistol mounts usually clamp onto the top strap or another part ofthe frame.
_____ 6. Modern scopes reproduce the image at about the same location as the shooter’seye.
_____ 7. Parallex occurs on images beyond 150 yards.
_____ 8. Because big game is generally more active at twilight, hunters can often benefitfrom scopes with large objective lenses.
_____ 9. When something goes wrong inside a scope, it can usually be repaired on the spot.
_____10. Bulls-eye shooters usually prefer a “duplex” scope reticle.
Check your answers with those on page 98.
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DRILLING AND TAPPING
Attaching mounts where no screw holes are present is a
more involved process, as it requires proper alignment and
drilling and tapping. Correct screw hole positioning will
depend on the type of mount, but it’s always wise to set up
this work in a drilling jig like those from Brownells and
Forster. A drilling jig will ensure that the screw holes are
true to the bore while facilitating correct drill and tap tech-
niques. At the very least, you must align the barreled action
in a padded vise on a level drill press table.
Note: Step-by-step drilling and tapping instructions follow
this procedural overview.
1. You should position bridge-type (one-piece) top mounts
so that the mount’s recoil shoulder (when it has one)
butts tightly against the rear of the receiver ring. Be sure
that any holes drilled in the receiver bridge are at least
inch from either edge. Position Weaver and most two-
piece mounts where they won’t interfere with
loading/ejection ports or the seating of locking lugs.
2. When employing a drill jig, some mounts may require
adjustment of the drill arm. You can do this without dis-
turbing correct alignment. When you don’t use a jig, drill
and tap one hole only, then attach the mount securely,
re-level if necessary, and center-punch the remaining
hole(s).
3. You secure side mounts by screws and/or taper pins.
Weaver and other firms currently offer a wide selection
to fit various modern rifles. They often attach by means
of a screw-on base plate shaped to fit specific receiver
walls. To determine the mount/base position (when not
utilizing predrilled holes), separate the barreled action
from the stock and place it (leveled) in a vise. Secure the
scope in the rings, join the mount and base plate, and
hold the arrangement in the desired location against the
receiver. On most guns this will be 1/4 to 1/2 inch in
back of the receiver ring. Clamp the arrangement in
place, and use a level to ensure that the mount is true
to the bore. Center-punch the middle screw holes, then
remove the mount/base and drill and tap these holes.
Always use a drilling jig when possible. Reattach the
mount/base and repeat the procedure for obtaining the
remaining screw holes. Use a Dremel tool to flush the
finish screws and pins to the inside of the receiver and
use a small grindstone to smoothly polish them.
4. You can accomplish side-mount installations on certain
lever-action rifles and shotguns by securing the mount
in holes provided for action or trigger assembly taper
pins. Secure the barreled action in a vise, then drive the
original pins out right to left with the muzzle pointed
away. Replace one pin at a time, inserting them left to
right, to avoid misaligning moving parts.
5. Most pistol mounts fit existing features, either clamping
to the top strap/rib, frame, barrel, and even the trigger
guard, or utilizing the rear sight screw hole. Ruger, for
example, mills their revolver ribs to accept clamp-on
rings, and single-shots like the T/C Contender and
Remington XP-100 come pre-drilled.
6. For some handgun mounts, however, you’ll have to drill
and tap screw holes. You must center and align them
with the bore on the revolver’s top strap, or on the slide
when using a side mount system on an auto loader.
Begin by leveling the frame or top strap in a padded vise,
then position the mount directly in line with the bore.
It’s also wise to file-fit the bottom of the base so that it
perfectly fits the gun’s contour. Clamp the base in place
and center-punch the screw holes through it. Separate
the base to drill and tap the first hole, then reattach to
confirm the position of the remaining holes. Pistol bases
must bear the brunt of fierce recoil, so be sure to
degrease all bearing surfaces and threads prior to final
installation, and use Loc-Tite to anchor the screws.
Grind and polish screws flush to inside surfaces with
a Dremel tool or files and emery cloth.
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Drill and Tap Procedures
A professional gunsmith will have a good drill press in his or
her shop. In no other type of gun work is this tool more
essential than when mounting sights. Hand drills can make
the screw holes, but without a press there’s no way to ensure
that they’ll properly align. A crooked sight is about as worth-
less as no sight at all, and to make matters worse, the gun
can become permanently marred if you make a mistake
aligning the holes.
For gun sight work, a drill press should have certain fea-
tures. You need a compound vise to put the work in the
proper position and to hold the gun steady and square. A
depth indicator and a positive depth stop are vital to prevent
over-deep holes and the ultimate error-penetrating the bore.
You also need good chuck that will close down tight enough
to grip drills as small as 3/64 inch when you make tiny holes
to roll pin a front sight blade.
The necessary drills will be smaller sizes; Nos. 28 and 31
wire gauge will get the most work, but you should have on
hand a wide selection, up to No. 16 perhaps, in the event
that some oddball job shows up. Short-length drills allow
more precision, have less “bend,” and are perfectly adequate
for shallow mount holes. Carbon steel drills will handle most
jobs as long as you don’t run them so hot to draw the tem-
per, as many gunsmiths today prefer the high-speed steel
type. For extremely tough receivers (the 1903A3 Springfield’s
hardness is legendary) solid carbide drills may be in order.
These, however, are quite expensive and must not be used
in softer steels. Additionally, a center drill will come in
handy. This is one that’s made extremely rigid by an over-
sized shank before ending in a very short drilling tip. Center
drills are ideal for starting and centering a hole, and to free
broken screws and taps.
As noted in the earlier sections on metallic sights and
scopes, a proper drilling jig is a great advantage in sight
installation.
Tools like the Forster Universal Sight
Mounting Fixture or Brownell’s SSR
Mounting System are engineered with broad
adjustment capability to secure and set up
virtually any long gun (Figure 38). You can
arrange the Brownell’s unit to accommodate
handguns and to install ribs. Such tools are
expensive, but the precision they facilitate
and the time they can save should profit
anyone mounting sights on a regular or
volume basis.
Both the Forster and Brownell sight mount-
ing jigs secure the gun by clamping it to
leveled V-blocks, and each provides a sliding
drill arm that travels slots parallel to the
V-block alignment. The drill arms, which
secure interchangeable bushings for both
drilling and tapping, move to the precise
location of the desired hole and lock into
place. Positioned directly over the top of
the gun, the superhard steel bushings
won’t allow drills or taps to flex or “wander.”
When you set up the work in these V-block
arrangements, screw holes are true to the
center of the bore and in perfect alignment
with one another.
B-Square’s Professional Drill Jig is a specialized fixture
made to position screw holes for popular scope mounts
on Springfields, Mausers, U. S. Enfields, and other similar
military bolt actions. It comes with interchangeable bars
(depending on the rifle) that furnish the correct hole spacing
in reference to the recoil shoulder, and also accepts various
bushings. B-Square also makes a mini Barrel Sight Jig that
combines a V-block base fitted with two No. 31 bushings and
a U-clamp that encircles the off-side of the barrel (Figure 39).
Gun Sights72
FIGURE 38—With the work secured in a Forster jigclamped to the press’s compound table, you canproceed drilling with assurance that the holes willalign perpendicular to the bore. The No. 31 drill,which matches the 6-48 screw, is the most commonsize for sight work.
Gun Sights 73
Another very similar jig is the Top Dead Center tool. With
both tools, you must first level the barrel in the vise, then
slide the jig to the correct placement and level it. This centers
the holes and makes them perpendicular. However, these jigs
are limited to use on round barrels and won’t service
receivers or pistol slide mounts or the like.
Whatever sight mounting fixtures are most practical given
the cost and the volume/type of work they’ll perform, they’re
virtually a must for professional sight mounting. Without
them (or some similar tool), you must make do by using the
mount itself as a guide and rely on squares, a center punch,
and a huge amount of luck.
The center punch, by the way, probably won’t be necessary
when using a close-fitting jig. Nevertheless, it behooves any
busy gun sight installer to keep some on hand just in case.
And when working without a jig, a 60 degree high-speed steel
punch inserted through the mount’s predrilled screw holes
will provide adequate hole positioning, so long as the work is
true. Keep in mind, however, that the impact of the punch
will further harden the surface of the steel.
We advise you that tapping proceed immediately after drilling
without disturbing the setup. Sight mounting work won’t
require a great variety of tap sizes. However, you should make
those on hand from the best quality carbon steel. Again,
some gunsmiths prefer those made from more expensive
high-speed steel. The 6-48, 3-56, and 8-40 sizes will be the
ones most frequently employed for sight screws, so a reason-
able quantity-enough to allow for some unavoidable breakage
is necessary.
FIGURE 39—B-SquareBarrel Sight Jig (Drawing
courtesy of B-Square,Fort
Worth, TX)
Note: The sizes we’ve mentioned so far aren’t the only sizes
you may need. You find a good selection that will cover near-
ly all sight mounting jobs in Brownell’s Drill & Tap Kit No. 2
(Figure 40).
Keep in mind that three different taps are necessary for any
screw hole that bottoms out without going all the way
through-the majority in sight mounting. The taper tap is
so-called because its long, gradual taper brings more teeth
to bear at a time; it’s the starter. The plug tap, with a bit less
taper, enlarges the hole and makes the threads more uni-
form. The bottoming tap has no taper and is flat on the end,
and is used to finish the hole.
Best for turning the taps is a T-handled wrench with an over-
head spindle that extends into the drill chuck. This ensures
that the tap work will line up precisely with the drilling. The
wrench turns freely (by hand power only, never using the
drill motor) on the spindle yet has no lateral movement that
could compromise the work or stress the tap. When using
tap wrenches lacking the connecting spindle, we strongly
advise you to have some kind of guide bushing in place to
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FIGURE 40—Brownell’s Drill &Tap Kit No. 2 (Photo courtesy
Brownells Inc., Montezuma, IA)
Gun Sights 75
prevent canting the tap. A possible alternative is the hand-
held Taprite Tap Guide, which will support the tap and keep
it from threading on a slant.
Drilling and tapping the small holes required for sight
mounting screws in hardened steel can be delicate work.
It is wise, then, for the beginner to practice first on pieces
of scrap steel before applying these techniques to a gun.
Drilling
The drilling procedure you use will depend
on whether or not you use a drill jig. When
you do use one, begin by determining maxi-
mum safe hole depth with a caliper or
micrometer, then setting the depth stop in
the drill press accordingly (Figure 41).
Before turning on the motor, lower the drill
once again to ensure there’s no binding as it
enters and passes through the bushing.
Be sure drills are sharp; if a point doesn’t
immediately take hold with moderate pres-
sure, it needs sharpening. Apply firm,
steady pressure, but never so much to
cause the drill to “spring.” This could result
in an enlarged, out-of-round hole, or a bro-
ken drill. Use plenty of top-quality cutting
oil, such as Tap Magic or Brownell’s Do-
Drill (STP motor lubricant will work in a
pinch), throughout the operation.
When no drilling jig is available, you must
secure the work in a padded vise mounted
to the press table, and true it with a try
square and level (Figure 42).
FIGURE 41—Before beginning any barrel drilling jobit’s absolutely essential to determine how deep thehole can be and to set the depth indicator/stop onthe drill press accordingly. A good rule of thumb isto leave at least as much metal as is removed. Lineup the work in the jig and true it with a level.
Gun Sights
Clamp the mount base in its intended position and level it,
then center punch one hole. (Completing work on one hole at
a time will ensure correct registration.) Remove the base and
begin the hole with the center drill, going only as deep as
the full diameter of the drill. Switch to the standard drill
and complete the hole. Move on to the next hole after tapping
the first and securing the mount in place with a screw.
Drilling and tapping hardened steel receivers may prove
extremely difficult, particularly when you don’t use a drilling
jig. You can usually remedy this by hand grinding off a tiny
spot of extra-tough surface metal before starting the hole.
However, the 1903A3 Springfield and some other receivers
have been hardened beyond surface depth and will require
spot annealing (softening) with a torch-at least for tapping.
Though annealing was once a virtual prerequisite for drilling
1903A3s, etc., the widespread use of today’s high-quality
high-speed steel and carbide drills makes it largely unneces-
sary. This does nothing to prepare the steel for tapping, so
there can be cases where spot annealing will prevent broken
taps and the frustration of removing them.
76
FIGURE 42—Always usetry squares and a levelwhen setting up drill andtap jobs. It’s preferable tosecure the barreled actionin a drilling jig or at thevery least a padded vise.
Gun Sights 77
Drill the holes as needed, then polish around them with
emery cloth; the polished spots should be about 5/16 inch
wide. Using a needle tip, set the oxyacetylene torch for a low,
lean flame and heat the metal-one spot at a time-to a deep
blue. Be careful not to let the steel begin to turn red or fur-
ther hardening will occur. Withdraw the flame slowly to allow
gradual cooling, then repeat the polishing/heating routine
two or three more times until the steel remains blue, rather
than brightening, when polished. You follow the same proce-
dure when it’s not possible to predrill holes, expect that
you’ll need to begin by spotting with a small hand grinder,
removing about inch of surface metal before heating. Don’t
begin drill or tap work until the metal has thoroughly cooled.
Tapping
Again, we highly recommend that you perform this job
through the bushing in a jig, using a wrench with a spindle
extension that you can secure in the drill press chuck. This
will hold the tap straight, evening out the pressure all
around, helping to prevent chipped teeth or even breaking
the tap (Figure 43).
As in drilling, it’s essential to freely use a
high-grade cutting oil. Turn the tap a half
turn then back off a quarter, turn and back
off. It may be smart to back the tap all the
way out on occasion and clear accumulated
chips. Stop tapping at once if you begin to
feel the tap give without actually turning in
the hole. Likewise, if the tap squeaks or
grinds, this probably means the tap isn’t
sharp enough. You need to either sharpen
it or swap it for a new one. Quit with the
taper and plug taps when you feel their
points bottom in the hole. Be sure to clean
out chips with a magnetic tip and debur the
surface with emery cloth before starting
screws.
FIGURE 43—It’s preferable to use a T-handled tap wrenchwith a free-turning extension spindle for threading sightholes. For the greatest precision, disturb the setup as little as possible when switching over from drilling to tapping, and engage the spindle in the chuck.
Attaching the Rings
Attaching the rings to the base is the next step. Separate the
halves of split rings (set aside the tops of those that come
apart horizontally) and if the base contains slots, indents,
or other recoil shoulders, be sure to properly seat the ring
clamps in these references. On Weaver-style bases, there’s
sometimes a small bit of play between the clamping screw
and its slot. So, be sure to check this and tap the rings for-
ward with a small mallet before tightening the screws. Also,
be sure not to confuse the old-style round clamp screw with
a new-style square base slot or vice-versa (Figure 44).
On the Redfield Jr. and other socket-type fixtures that are
rotated into a secured friction fit, use a screwdriver handle,
a dowel, or small piece of pipe rather than attempting to
crank it in with the scope. Do this a time or two until it
seats properly before setting the scope in place.
Note: It’s not unusual to find overly long mount screws that
bottom out before getting really tight. In the case of Weaver
clamp screws, it’s also not unusual to find screws that pro-
trude into the screw head slot and make it impossible for the
driver to gain a solid hold. You must shorten them, taking
care not to damage threads.
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FIGURE 44—Reliable yet inexpensive, the Weaver topmount is probably the all-timebest-selling scope mount.Weaver top mounts fit thereceivers of practically all modern rifles. Before tighten-ing the ring screws duringinstallation, tap the ring for-ward to be sure no play existsin the crossbolt slot.
Gun Sights 79
Positioning the Scope
The exact position of the scope depends largely on the shoot-
er’s personal eye relief, which won’t be the same from one
individual to the next. For that reason the shooter should
be present when the scope is being mounted.
For rifle and shotgun scopes, the shooter stands or sits
shouldering the gun as he or she would in a normal firing
position. Be especially sure that the head is in its natural
position on the stock. Also, the shooter should wear clothes
he or she wears when using the gun. For cold-weather hunt-
ing, this means heavy garments or several layers. Handgun
shooters should grasp the gun with their customary hold,
but they may also need some external support.
Ensure that the rings are the correct size for the scope tube
and determine the desired ring height. Rings generally come
in low, medium, and high variants; of these, low rings are
the most popular. Optimum height depends on how the
shooter cheeks the stock. Raising one’s head from the
cheekrest to see through a high scope leads to poor shooting.
However, the size and position of the scope’s ocular bell may
also require higher rings to clear a bolt, hammer, safety, or
other moving parts. At times you can alter the part, such as
changing the angle of the bolt handle or adding a hammer
extension, but a simpler alternative that works in many
cases are extension rings. These are offset from the bases to
allow the scope to be placed out of harm’s way. Unfortunately,
you can only slide a scope so far in either direction before
compromising eye relief. When this happens, high rings,
a gunsmithing alteration, or a different scope may be the
only option.
Place the scope in the rings and tighten the screws until they
hold it snugly but still allow it to move. Then slide the scope
toward or away from the shooter’s eye until the shooter sees
the entire field of view. With modern rifle scopes, this eye
relief zone may extend an inch or more, so for the sake of
speed it may be preferable to find the midpoint. On hard-
kicking magnums, it’s wise to place the scope toward the
front of available eye relief (that is, with maximum distance
between the scope and the eye). This makes it less likely for
the shooter to get conked on the head during recoil.
Once you determine proper eye relief, set the gun in a padded
vise or cradle and make sure it’s level. Without disturbing
the position of the gun, rotate the scope (taking care not to
shift it forward or backward) until the vertical crosshair or
post is also perfectly vertical. This step prevents scope canti-
ng, which can lead to sighting errors. Tighten the screws
with partial turns, alternating from side to side and ring to
ring. Don’t attempt to secure any one screw or either side
too quickly, or the scope may become pinched off its vertical
axis. Alternate tightening allows even spacing where the ring
halves meet. Ideally, the halves should be in contact, but this
isn’t always the case. Small gaps are sometimes present. For
strength and looks these gaps should be even, so you can
fill them with tiny spacers. It’s not necessary for ring screws
to be so absolutely tight as mount base screws, and over-
tightening can mar or dent the scope tube.
Sighting may reveal that the scope doesn’t have sufficient
adjustment to obtain the desired zero (this rarely occurs
with late-model guns, but it can crop up on older military
conversions, air rifles, and others). Then you can remount
the scope in adjustable mounts or by using shims. There
are a number of adjustable mounts on the market, some for
both elevation and windage, some for one direction or the
other only. Don’t confuse them with micrometer-style target
mounts that must make fine adjustments for scopes with
fixed reticles. Rather, they’re limited to gross adjustments
and must be used in concert with internal adjustment. When
using one, begin it at the middle of its adjustment range,
then move it only when necessary.
Gun Sights80
Gun Sights 81
Shims, both manufactured and homemade, can also solve
minor elevation deficiencies. Factory shims made of super-
thin steel or other material fit under mount bases and come
predrilled in various combinations to match the bases’ screw
holes. You can fashion home versions using anything from
steel sheeting to an old business card. When using any
material that has even the slightest degree of “give” (like
paper), be sure that screw tightening has crushed the “give”
out of it. Similarly, you can cut a shim to fit the inside of a
ring; electrician’s tape (sticky side down) makes for a neat job
and can be used in two or three layers. “Crushed” under the
pressure of the ring screws, it will also ensure against scope
slippage. For aesthetics’ sake, you should touch up any
shims that are visible after installation with black ink or a
bluing retouch marker (Figure 45).
FIGURE 45—Birchwood Casey offers a trio of touch-up pens designed to make it “quick and easy” to keep bluedsteel and black anodized aluminum or other black-painted metal surfaces looking good on guns. (Photo courtesy
Birchwood Casey, Eden Prairie, MN)
Gun Sights82
Self-Check 4
1. You should use _______ _______ like Tap Magic and Brownell’s Do-Drill during drill andtap operations.
2. You may need to spot _______ with a torch to produce screw holes in 1903A3Springfields and other hardened receivers.
3. When tapping a screw hole, never apply _______ _______ if the tap begins to squeak orgrind.
4. A _______ tap enlarges a drill hole and makes threads more uniform.
5. Using a tap wrench with a spindle extension secured by the drill press chuck holds thetap _______.
6. The drills that get the most work in sight-mounting jobs are Nos. _______ and _______wire gauge.
7. A gunsmith’s drill press should be equipped with a chuck that will close tight enough tohold a _______ drill.
8. A _______-bodied, _______-tipped center drill is useful for starting a hole.
9. Using a drilling jig, like those from Brownells and Forster, is the best way to ensure_______ _______ sight mount holes.
10. Drilling jigs feature interchangeable super-hard steel _______ to keep drills from “wandering” off precise screw hole locations.
Check your answers with those on page 98.
Gun Sights 83
SIGHTING-IN
With the scope successfully mounted, it’s now time to zero
the rifle’s shots to hit where the reticle indicates. This is
somewhat easier to accomplish with a scope than iron sights,
since the aiming point is so much more precise. By employing
the correct techniques, you can complete sighting-in quickly
using less than a box of ammunition. By contrast, an unpre-
pared trip to the range can cause no end of frustration.
Before you commence the sighting-in, and even before you
touch the first adjustment knob, you must focus the scope
for the shooter’s eye. You can do this anywhere, though out-
side using a neutral background free of distracting elements
is probably best. It’s also useful to view some distant objects
during this procedure.
If the shooter is going to wear glasses or contact lenses when
using the rifle, it’s important for him or her to have them on
at this time. Quickly look through the scope at the sky or
some other well-lit, uncluttered background and note the
sharpness of the reticle. If it takes a moment for the eye to
bring the background into focus, then you need to refocus
the scope. Suppose it’s immediately sharp and clear all the
way to the end of the crosshairs and
remains so when you repeat the exercise a
few times at, say, three minute intervals.
Then, reposition the scope to look at some
object 100 yards or more away. If the eye
can shift back and forth from the crosshairs
to the object and both remain sharp without
a momentary lapse, then you don’t do any-
thing further (Figure 46).
FIGURE 46—For those who prefer sighting-in on roundbulls-eyes, Birchwood Casey offers a target spot assort-ment for creating instant bulls-eyes. The target spots areprinted with a high contrast, radiant-red fluorescent colorthat effectively creates a sharper sight picture and bulletholes which are more clearly visible. (Photo courtesy
Birchwood Casey, Eden Prairie, MN)
You correct unsatisfactory focus by loosening the lock ring,
and turning the ocular lens in or out until a tack-sharp,
quick-glance focus is evident (being careful not to screw it
all the way off). Repeat this test several times, being sure to
refocus the eye on something else during the look-away inter-
vals. Lock the eyepiece into place and the focus should
remain correct so long as the shooter’s vision is the same.
Because everyone’s eyes are different, it’s essential that you
set the focus for the person who will use the scope.
Bore Sighting
Bore sighting is a handy shortcut to establishing a zero. You
accomplish bore sighting by aligning the reticle on a down-
range target that appears centered when looking directly
through the barrel. Most shooters favor a round bulls-eye,
but this method will also work with some kind of “X” or
cross, or even with target squares (Figure 47).
Bore sighting works best with bolt actions and single shots,
but it can work with levers, pumps, and semiautos by
employing a chamber inspection mirror.
Begin by securely resting the rifle on a bench rest pedestal,
sandbags, or some other solid rest. Remove the bolt, open
the action, or position the mirror-whatever it takes to get a
clear look down the bore. Shift the gun until the target is as
perfectly centered as possible.
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Gun Sights 85
From this point, you must be very careful not to move the
gun even the slightest bit. Proceed to look through the scope
from the normal shooting position. In all likelihood, you
won’t find the reticle lined up on the target. Hold the rifle
firmly, still taking care not to move it at all, and very gently
turn the internal adjustment screws or knobs until the reti-
cle is precisely imposed over the target (Figure 48).
That’s all there is to bore sighting, but keep in mind that it’s
not an exact science. It’s likely to put the first shots some-
where on the target paper, but further fine-tuning will be
necessary. Most shooters bore sight at 100 yards, the dis-
tance they’ll be zeroing for. Even though most know enough
to use very large targets, there are times when the shooter
won’t find shot holes when the test firing finally begins. This
FIGURE 47—Those who prefer precision squares will appreciate the superimposed grid pattern offered onBirchwood Casey’s traditional targets. Each target contains multiple faces for more shots per sheet. (Photo cour-
tesy Birchwood Casey, Eden Prairie, MN)
Gun Sights86
can occur when barrels are slightly bent or the scope is
slightly out of alignment with the bore, but even these guns
can be bore sighted, zeroed, and shot accurately. The answer
here is to move the target closer-50 yards, 25 yards if need
be. Repeat the bore-sighting procedure and try a shot or two.
When you find the shots at closer distances, it may be neces-
sary to bore sight again when the target is farther down
range.
Modern technology provides a gadget to bore sight any type
of scope indoors. This handy little device is a collimator, and
for anyone responsible for bore sighting or zeroing several
guns, it can be a real time-saver. At the heart of the collima-
tor is a close-tolerance rod called a spud that extends a cou-
ple of inches into the muzzle. You then attach the spud,
which you select to fit the bore diameter, to a small optical
unit containing visible crosshairs and reference marks, or
FIGURE 48—When bore sightinga rifle, the procedure begins bycentering the target as oneviews it through the bore (bot-tom). Then, adjust the scope’scrosshairs until they also centeron the bulls-eye for a reasonablyreliable preliminary zero.
Gun Sights 87
perhaps a grid. The user simply aligns the scope’s reticle
with the collimator’s horizontal and vertical axes and the
optical bore sighting is complete. Again, even a slight bend in
the barrel will fool the collimator. In such cases, revert to
conventional bore sighting at short range (Figure 49).
Final Sighting
Though bore sighting or using a collimator will usually put
one “on the paper,” you should still the take a gun out to the
range and ascertain its zero at a suitable distance. Most
often the distance for centerfire rifles is 100 yards, the com-
mon length of U. S. rifle ranges. This makes for convenient
scope sight adjustments, since each click will move the cor-
responding reticle a fraction of an inch per 100 yards. Most
click adjustments nowadays are good for one-quarter inch at
100 yards, but you’ll also see scopes with one-third and one-
half inch graduations.
You should zero rimfire rifles and slug shotguns at 50 yards,
since 100 is at the upper limit of, or beyond, their effective
range. Likewise, you should sight-in scoped pistols at 25
yards, unless they’re long-barreled single-shots chambered
for a rifle cartridge, whereupon 50 or 100 yards would be
more appropriate.
FIGURE 49—Containing a grid orcrosshairs in its small opticalscreen, a collimator allows con-venient preliminary sight-in justabout anywhere. One selectsthe correct interchangeablespud to match the size of thebore, inserts it in the muzzle,then adjusts the scope reticle to overlay the collimator’s reference markings.
Gun Sights
You should do all sighting-in work from an absolutely solid
rest. At the very least this means sandbags on a stable
shooting bench. A formal bench rest pedestal equipped
with an elevation wheel and accompanied by a rear bag is
markedly better. Relying on a balled-up jacket or a small,
clamp-on bipod is often a futile exercise. Handgun shooters
will achieve even better results with a Ransom Rest, a spe-
cialized clamping device that completely supports the pistol,
which in turn is fired by a lanyard attached to the trigger.
To achieve the final sighting, sit comfortably and lean into
the gun in the classic bench rest posture. Square the butt
securely on your shoulder, grip the stock wrist lightly with
your trigger hand, and use your off hand to pinch minute
aiming adjustments into the rear bag. On particularly hard-
kicking guns, you may need to use your off hand to control
the forend, which has the tendency to jump off the rest.
When that happens, the shooter usually gets smacked by
the scope, something no one really enjoys.
Fire the first shot and then find it on the target. You can
often see it through the scope (depending on the magnifica-
tion power and the bullet’s caliber), but a surer bet is to use
a spotting scope (Figure 50).
If it doesn’t appear through the optics at hand, then you may
have to walk down-range-only when safe to do so-and locate
it. If the bullet hole isn’t on the paper (allow for plenty of sur-
face area when getting started), move the target closer by at
least half the distance and try again.
If the first bullet hole isn’t more than several inches from the
point of aim, continue firing a three-shot group. Figure that
the gun’s average point of impact is the center of the three
shots. That point must be moved to occupy the same spot
as the original point of aim, a shift accomplished with the
scope’s internal adjustments. Use a coin or screwdriver to
make the change unless the scope has knob adjustments.
It’s important here to estimate the required move and to
know exactly how far each adjustment click will move the
shot. The adjustment mechanisms of modern scopes are very
reliable, but occasionally they’ll hang up, a commonplace
mishap with older models. If the reticle doesn’t seem to
respond, give the turret a sharp rap with your knuckle and
fire another shot.
88
Gun Sights 89
Should the first hit land way off the mark, however, make
the initial sighting change right away-no need to fire three
rounds out of the ballpark. If several subsequent shots fail to
form a group, recheck all mount, ring, and action screws.
They must be tight! Poor shooting technique or an unstable
rest can also lead to unsatisfactory groups. Some loads sim-
ply perform poorly in a given gun; if this happens, try a dif-
ferent load. The purpose here isn’t to shoot tack-hole clus-
ters, but they must be tight enough to provide a definite
point-of-impact reference.
Note: Always make it a practice to center groups, not indi-
vidual shots. Continue with three-shot groups throughout
the zeroing procedure.
Make adjustments with purpose; figure the number of clicks
needed to move the group and make them. Don’t creep to the
center of the target. When a gun is grouping satisfactorily,
it shouldn’t require more than three or four adjustment
series to reach the desired zero. Be sure to allow enough
time between shots, however, to prevent barrel heating from
producing “fliers.”
FIGURE 50—Bushnell’s 18-36XSentry spotting scope provideswide field viewing at low powerand sharp close-up detail at high power. A built-in peep sight aids fast target acquisition.(Photo courtesy Bushnell, San
Dimas, CA)
Scope zeroing is a service extended by many professional
gunsmiths after performing work or following the purchase of
a new firearm or scope. For the most part, a gunsmith can
establish a workable zero for the gun no matter who subse-
quently shoots it. There will be minor differences from person
to person, however, due to the way each one shoulders or
grips it. By all means prevail on customers to get out and
practice, if for no other reason than the safety factor of being
familiar with one’s equipment.
Unless you have several guns to sight-in, this practice can
eat into valuable shop time. You can charge a fee for the
service of course, though if it’s reasonable-say $25-it will
probably just cover expenses. Don’t overlook the customer
service value and the goodwill generated. These certainly
contribute to the gun professional’s reputation. In the long
run, this kind of extra effort could pay solid dividends.
Alternately, you could limit such service to bore sighting or
collimating. For the majority of customers this will be entirely
satisfactory-even at the cost of a few dollars. They’ll soon
head for the range to try out the new or repaired gun or the
new scope. When the gun and scope leave the shop with pre-
liminary sighting-in already accomplished and the first shot
prints cleanly on the target, it reflects on the gunsmith’s pro-
fessionalism. Be sure that the customer realizes that bore
sighting is merely a preliminary measure, and he or she still
needs to complete the sighting-in job. Done in-house with a
collimator, this will require only a few minutes. Also, if you
do it in the customer’s presence, he or she will likely leave
with a greater degree of confidence in the purchase or the
work that you performed.
Bolt Handle Alteration for ScopeMounting
On certain older military bolt-action rifles, it’s necessary to
change the angle or shape of the bolt handle to clear a low-
mounted scope. On these rifles, a scope can prevent the han-
dle from rotating into its uppermost position. They include
the 1903 Springfield, Krag, Arisaka, and Mauser. Other rifles
may need bolt alteration. You can achieve the alteration in
Gun Sights90
Gun Sights 91
two ways: 1) by forging the handle with a torch and bending
it, or 2) by hacksawing the old handle off, leaving a stud onto
which you weld a reshaped or custom handle. Most gunsmiths
usually prefer the second method, since it subjects the bolt
to somewhat less heat. Both methods require advanced gun-
smithing skills and only those who have the proper training
should attempt them. The intense heat involved in both
cases can damage locking lugs and other bolt parts if it’s not
confined to the handle.
In addition to the welding apparatus and basic shop tools
needed (hacksaw, grinder, files, etc.), there are a number of
specialized commercial jigs that facilitate these conversions.
Among these are the Three V Bending Block for the forging
method, and Brownell’s Bolt Welding Jig for cut-and-weld
jobs. Another valuable aid offered by Brownells is a heat
sink, a fixture that screws into the rear of the bolt and draws
heat away from the rest of the bolt body. These come threaded
for Springfield, Mauser, and Enfield bolts, and we recommend
you use them in conjunction with that firm’s Heat Stop, a
paste that effectively controls the transfer of heat within a
bolt.
Note: Heat Stop may also be beneficial in any sight installa-
tion that involves direct soldering or welding.
Procedure
You perform bolt handle conversions as follows. We stress
once again that only qualified individuals should perform
these tasks.
Forging. Disassemble the bolt, insert a heat sink in the rear
end, and coat the entire bolt body with plenty of Heat Stop
paste. Secure the bolt body in a Three V block or similar tool,
and place the arrangement in a heavy vise. With a large jet in
the oxyacetylene torch, heat the bolt handle quickly until it’s
cherry red and the metal is almost molten. Take care not to
scorch the steel by allowing it to contact the bright, central
oxygen cone visible within the flame, and make sure the
locking lugs and bolt face don’t heat up.
Grasp the knob with a forming tool (a flat piece with a
tapered hole at one end) and pull it downward to create a
right angle just out from the bolt body. Curve it up at the
very end so the knob will clear the stock, and if desired for
looks, rake the handle back a bit. (You can also bend it with
a medium-weight machinist’s hammer, though not with the
same degree of control.) Allow the setup to air cool slowly
before removing it from the block. After removing the Heat
Stop, file off any heat scale, regrind the bolt handle to its
original width if any deformation has occurred, and polish
it with a buffing wheel or emery cloth.
Note: The above procedure differs slightly from that discussed
in Basic Metalwork and Machine Tool Operation. There are
various methods for forging bolt handles.
Welding. Disassemble the bolt, secure its body in a vise,
and hacksaw the handle with a diagonal cut running from
the edge of the shank taper (where it changes from flat-sided
to round) at a 45 degree angle. Often it’s necessary to anneal
the area of the cut. Just be sure not to allow the heated
metal to begin to turn from bluish-gray to red, as this will
reharden it. At this point, determine exactly how much you
have to shorten the handle to provide scope clearance and
cut off the excess. If you’re changing the handle’s shape,
forge it as described above, holding it in position in the vise.
As an alternative to the original, there are a variety of after-
market bolt handle knobs available for such conversions, and
many gun owners opt for one with better looks.
Grind the end of the remaining handle shank so that it forms
wide “Vs” at the weld joint along the angled edge of the bolt
stub. This gives the weld maximum surface area. Clean up
weld joint surfaces, insert the heat sink, and position/secure
both pieces in Brownell’s bolt welding jig or a similar fixture.
This will hold the work securely without the risk of displac-
ing it with an unintended bump and it allows convenient
access to both sides. Encase the bolt body in a heavy appli-
cation of Heat Stop paste. Proceed with welding, using a mild
steel rod for both arc and gas welders. Torch welders should
use a medium-sized jet, taking care not to pull away the
flame too fast. Fill in the “V” notches all the way, working
from the middle up and out to the sides until the bead slightly
Gun Sights92
Gun Sights 93
overfills the notch. Be sure the bead fills in solidly by guiding
any scale that forms off to the side where you can file it away
later. Timely completion of the welding will minimize the heat
reaching the rest of the bolt. Air cool, then check the weld to
make sure that it’s solid; fill in if needed. When the welding
is complete, remove any accumulated scale, then grind, file,
and polish to obtain a pleasing handle contour.
Quite often it’s necessary to cut a relief notch in the receiver
in order for the new bolt handle to close fully. With a milling
machine or files, shape this notch to match the handle shape.
Make it just deep enough so there’s minimal clearance on the
inside edge of the receiver and the locking lugs can fully lock.
Be sure that this position doesn’t interfere with the functioning
of safeties and cocking/extracting cams. It may be necessary
to reheat treat the entire bolt after welding or forging. Only
qualified persons should attempt this job.
Safety Replacement for Scope Mounting
Just as it’s often necessary to alter bolt handles when
mounting a scope on certain military (and similar) rifles, you
may also have to install a new safety. Original safeties on
military rifles, built into the back of the bolt, rotate vertically
in a semicircular arc that’s blocked by the eyepiece of practi-
cally any low-mounted scope. You need to use a safety with
an alternate operating movement with this type of mounting.
Fortunately, a number of replacement models are available.
Some replacements work in essentially the same manner
as the originals, except that their movement arc, shortened
from 180 degrees to 70 degrees, stops just short of the scope.
Others adopt the “side-swing” design from the Winchester
M70. This type rotates horizontally back toward the shooter,
never moving up toward the scope.
The task of installing aftermarket safeties varies with the
individual model. Some, like the Buehler Low Safety, may be
simply exchanged with no machining of other parts. Other
jobs, such as required for the Chapman and DeLorge
safeties, involve using a milling machine and preferably a
milling fixture, as available from Chapman. Still others, like
the Precise Metalsmithing and Dakota conversions, replace
Gun Sights
the entire bolt shroud, containing the new safety therein.
Regardless of the type, you must carefully fit them to ensure
sufficient cocking piece/sear clearance. Inadequate clearance
could lead to slam-fires or firing as the safety disengages.
Warning: Any such unintentional firing is dangerous, and
could lead to property damage, injury, or even death. The
serious consequences involved demand that only qualified
individuals attempt safety installation.
Carefully read the manufacturer’s instructions and be sure
you fully understand them before beginning the conversion.
If any questions remain, don’t hesitate to contact the manu-
facturer. It’s also wise to consult with a gunsmith experi-
enced in this kind of work.
Installation Procedures
Following are installation procedures for the Buehler and
Precise Metalsmithing safeties, as neither requires machine
work. Again, we stress that only qualified professionals carry
out this work.
Buehler. Disassemble the bolt, remove the old safety, then
screw the bolt sleeve back into the body. At this point the
Buehler safety is dismantled. Compress the spring inside
the hole in the mounting pin and slip the assembly into its
position in the bolt sleeve. Install the safety lever and secure
it with the setup screw. For smooth operation, bevel the
bearing surface on the left side of the cocking piece to a
45 degree angle. When installed properly, this safety cams
the striker clear of the sear while holding the bolt in the
closed position. Excessive wear on the sear and striker engag-
ing surfaces will sometimes allow the striker to protrude too
far forward (in the cocked position) for the safety to function
correctly. When this happens it may be necessary to grind
back the shoulder on the cocking piece. Check the manufac-
turer’s instructions for the correct clearance between the bolt
head and the striker engagement surface.
Precise Metalsmithing. Disassemble the bolt and with the
safety lever in the middle position, screw the new shroud/
safety assembly into the bolt body. The plunger will seat in
the detent slot when the shroud is in the correct position.
94
Gun Sights 95
Check to see that the bolt will close and that the safety trav-
els smoothly throughout its arc of movement. If there’s any
interference or binding in the safety, lightly file/polish the
safety detent at the rear of the bolt. The safety lever should
cam the cocking piece backward, providing positive clearance
between the cocking piece’s engagement ledge and the sear.
This clearance should be no less than .3 inch with the original
trigger, perhaps a little less with a modern replacement trigger.
Check this clearance with a vernier caliper or feeler gauge.
If it’s insufficient or when operation isn’t smooth, polish the
30 degree bevel on the cocking piece’s camming surface or
file the sear engagement ledge to shorten it as necessary.
Note: The contact face on the cocking piece engagement
ledge must be square and perpendicular to the bolt center
line. Also, when you perform any filing on bolt parts, you’ll
have to reheat treat.
Gun Sights96
Self-Check 5
Indicate whether the following statements are True or False.
_____ 1. Inadequate cocking piece/sear clearance never leads to dangerous situations likeslam fires or firing when the safety is disengaged.
_____ 2. When forging, heat with an oxyacetylene torch until the shank turns cherry red.
_____ 3. Altering bolt handles for scope installation is a job that can easily be performed bymost gun owners in home shops.
_____ 4. For low-mounted scopes on certain military bolt-action rifles, replacement safetiesmust shorten or redirect the movement.
_____ 5. Properly reshaped bolt handles never require receiver relief cuts and/or stock inletting.
_____ 6. When the Buehler safety is installed properly, it cams the striker clear of the sear.
_____ 7. Bolt alteration is accomplished in two ways: forging and welding.
_____ 8. Installing a Chapman and Delorge replacement safety requires use of a millingmachine.
_____ 9. The Three V Bending Block bolt alteration tool is used for welding.
_____10. The proper shape for bolt handle shank stubs prepared for welding is rounded.
Check your answers with those on page 99.
97
Self-Check 1
1. True
2. True
3. False. Match apertures are considerably smaller-.05 inch
is a common size and some are even tinier.
4. False. The right side should be a few thousandths of an
inch larger.
5. True
6. False. Shooters have resorted to applying bright paint on
the rearward face.
7. False. They used front and rear rifle sights as early as
1500.
8. True
9. False. You should never penetrate the bore when drilling
holes for barrel sights because this ruins the barrel.
10. False. These are rear sight styles.
Self-Check 2
1. Shotgun beads
2. military, law enforcement
3. circular
4. dots, outlines, inserts
5. color, head diameter, shank size/thread
6. short
7. combat
8. windage and elevation
9. hacksaw
10. square
An
sw
er
sA
ns
we
rs
Self-Check Answers98
Self-Check 3
1. True
2. True
3. True
4. True
5. True
6. False. This was a characteristic of earlier scopes.
7. False. Parallex occurs on very close images, usually
inside 50 yards.
8. True
9. False. You can’t repair the scope at the range or in the
field.
10. False. Big game hunters prefer a duplex scope reticle.
Self-Check 4
1. cutting oils
2. anneal
3. added pressure
4. plug
5. straight
6. 28, 31
7. 3/64 inch
8. fat, short
9. correctly aligned
10. bushings
Self-Check Answers 99
Self-Check 5
1. False. It could lead to slam fires or firing when the safety
is disengaged.
2. True
3. False. This requires advanced gunsmithing skills.
4. True
5. False. A reshaped bolt handle may require cuts or inlet-
ting.
6. True
7. True
8. True
9. False. It’s used for forging.
10. False. The bolt handle shank stubs are V-shaped.
Self-Check Answers100
NOTES
101
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Gun Sights
When you feel confident that you have mastered the material in this study unit, complete the following examination. Then submitonly your answers to the school for grading, using one of the exam-ination answer options described in your “Test Materials” envelope.Send your answers for this examination as soon as you completeit. Do not wait until another examination is ready.
Questions 1–20: Select the one best answer to each question.
1. When zeroing metallic rifle sights,
A. divide the front and rear barrel diameters by two and subtract the difference.
B. move the rear sight in the direction you want the shot tomove.
C. move the front sight in the direction you want the shot tomove.
D. file down the front sight.
2. Bore sighting means
A. mounting the scope as close to the bore as possibleB. being able to place the shots so that they are touching in
the bulls-eye.C. centering a target when viewing down the bore, then
adjusting the crosshairs to the same aiming point.D. using a shotgun with no bead or rib.
EXAMINATION NUMBER:
Whichever method you use in submitting your examanswers to the school, you must use the number above.
For the quickest test results, go to http://www.takeexamsonline.com
Ex
am
ina
tion
Ex
am
ina
tion
02530700
Examination102
3. Installing a Smith & Wesson-type adjustable rear sight on a Colt Government Model .45requires
A. removal of the Smith & Wesson logo.B. a ramp front sight.C. inletting a shallow recess into the top of the slide.D. drilling a slot behind the ejection port.
4. Scope sights have really won the public’s favor since
A. Kepler refined the telescope.B. Civil War snipers used them.C. mass production began in the early twentieth century.D. they were made brighter and more reliable following World War II.
5. The key to proper tap procedure is
A. a straight tap with sharp teeth, plenty of oil, and gradual turning.B. beginning with slightly undersized taps and finishing with slightly oversized taps.C. uninterrupted turning to ensure unbroken threads.D. letting the drill press motor do the harder jobs.
6. Today’s scope mounts are very easy to install because
A. the steel in modern rifle receivers is relatively soft, and therefore easy to drill and tap.B. they simply replace the factory iron sights.C. they can be attached by electromagnetics.D. they’re manufactured to fit factory-drilled screw holes and/or other design features.
7. Open sights, the most common of all metallic rifle sights past and present, consist of
A. two aperture sights. C. a long tube with no lenses.B. a shallow notch and a bead or post. D. an extra-large peephole.
8. A collimator is a handy device for gunsmiths because it
A. helps determine the correct height for scope rings.B. allows them to accomplish preliminary sight-in anywhere.C. helps the shooter judge the distance to the target.D. helps hold the gun straight for proper sight-in.
9. You level side-mounted rear aperture sight holes by
A. truing with try squares and/or a drilling jig.B. drilling just one hole at a time.C. bore-sighting with the sight clamped in place.D. placing a machinist’s square on the front sight.
Examination 103
10. Rifles that often need bolt handle alteration and safety replacement for scope mountinginclude
A. older military semiautos like the BAR, M-1, and AK-47.B. any rifle chambered for a magnum more powerful than .300 Winchester Magnum.C. lightweight “mountain” rifles.D. certain military bolt-actions, that is, Springfield, Krag, Mauser, etc.
11. Ideally, a drill press used for sight mounting should be equipped with
A. rubber bushings in the sight mounting jig.B. a handle with large knobs, interchangeable chucks, and carbide bits.C. one forward speed and reverse capability.D. a compound vise, depth indicator and stop, and a tight-closing chuck.
12. Which hand tools do you need for cutting a dovetail sight mounting slot?
A. A center punch and an oxyacetylene torch B. A Dremel tool, a cold chisel, and an emery cloth C. A scriber, a hacksaw, and a 60 degree file D. Vise grips, a hand drill, and taps
13. When applying heat for bolt handle forging or welding, one must never
A. allow scale to form.B. allow the bolt handle to get red-hot.C. use an electric arc welder.D. allow excess heat to reach the bolt’s locking lugs.
14. Competitive shooters favor rear aperture sights because the sights
A. facilitate natural sight alignment and precise adjustments.B. worked great for the buffalo hunters.C. are very easy to mount on dovetail grooves.D. don’t cause as much glare as open sights.
15. What are the two basic categories of handgun sights?
A. Paine and bead C. Windage and elevation B. Top-strap groove and beadD. Fixed and adjustable
16. Safety conversions are potentially dangerous! Always
A. checker the thumbpiece to prevent slippage.B. ensure that the new safety holds the striker or cocking-piece engagement ledge clear
of the sear.C. ensure that the safety can never be manipulated when there are rounds in the
magazine.D. affix the new safety to the cocking piece with a set screw or solder.
Examination104
17. Methods used for mounting shotgun beads are
A. screw-in or drive-in.C. cutting a dovetail in the rib or barrel.B. clamp or weld onto the ribD. with a Top Dead Center tool and a heavy hammer.
18. Essential tools for all scope mounting jobs are
A. C-clamps and a set of socket wrenches.B. a solder iron and a Dremel tool.C. a tight-fitting, hollow-ground screwdriver or Allen wrench and Loc-Tite.D. a soft brass drift punch, small mallet, and magnetic level.
19. When working on the sights of a handgun that has “fixed” sights, the most likely job is
A. replacing the hammer.C. milling a new rear notch.B. replacing the front sight.D. installing drill-rod pins through the old rear sight.
20. Scopes with high magnifications have advantages and disadvantages, such as
A. fine adjustment capability but small exit pupils.B. the target appears much closer but field-of-view is diminished.C. easy-to-see reticles but critical eye relief.D. small size but poor twilight capability.