Ballistics

Specialty BinderBallisticsTable of ContentsObjectives, Introduction, and Firearm AccuracyFirearm Accuracy Increasing the Force of the Bullet Improving the Rate of Firing and Firing ReliabilityHandgunsRiflesShotgunsAmmunition Ballistics Collection and Preservation of Firearm Evidence (1 of 6)Laboratory Examination of Firearm EvidenceObjectivesGain an understanding of..-using rifling marks on a bullet for identification of manufacturer of gun fired-difference between rifles, shotguns, revolvers, semi-auto pistols-compentents of ammunition -The integrated ballistic identification system- ways to restore obliterated firearm serial numbersIntroductionRecovery of firearms or related items is very important to the investigation of crimes involving firearmsFirearm technology focuses on 4 major problemsProjectile accuracyIncreasing projectile forceIncreasing firing rateImproving reliability of firing mechanismFirearm AccuracyLengthening of barrels can improve firearm accuracyRifling: spiral grooves on barrels inner surfaceImproves accuracyCan identify weapons manufacturerImprints different scratch patterns on bulletsCaliber: the internal diameter of the gun barrel Firearm AccuracyThe amount of grooves and lands and the direction and rate of twist in a gun are characteristic of one product and one createrStriations are formed possibly from imperfections of the surface of the broach cutter or from shards of steel that is made into wedes when it is caught between the broach cutter and the barrel wallThe individual marks left on bullets are individual marks that allow a forensic specialist to match the bullet to the gun it came fromIncreasing the Force of the BulletThe larger of caliber the weapon is, the greater the kinetic energy it has when fired from the gunThe larger the caliber, the wider the bore of the barrel and the larger the bullet is has to be to fill that boreThe greater the projectiles velocity, the greater kinetic energy that the bullet hasImproving the Rate of Firing and Firing ReliabilityFlintlock rifle: a single-shot rifle that uses a spark to ignite the gunpowder that is loaded in the barrelThe firing mechanism was temperamental and very difficult to fire into the rainThe rate of firing was also slow

HandgunsCompact weapons that are able to fire with one handMultiple shots without the need of reloadingShoots bullet fast enough to stop an attacker but recoil on gun not too powerful to force gun out of gunmans handHandgunsRevolversGenerally 6 shots Easy to use and handle Cheap to purchase and easy to clean Theres single and double action Single the hammer has to be cocked Double you just need to pull the trigger HandgunsRevolversBarrel length is short making it easy to conceal Cartridges stay in gun after being shot HandgunsSemiautomatic pistols Uses recoil from gun to reload the next round into chamberHolds anywhere from 10 to 19 rounds Are more complicated and jam sometimes After each shot the gun ejects the cartridge which are found at crime scenes HandgunsSilencersAttach to a handgunReduce the amount of noise generated by firing the weaponHandgunsSubmachine gunsCan fire automatically like a machine gun but use pistol ammunitionAre small and lightweightPreferred by security details because they are small and easy to conceal

RiflesDiffer from handguns in that they have a long barrel and butt stockAre hard to conceal, but much more accurate than handgunsCome as single-shot and multiple-shot modelsAre popular choices for hunters

ShotgunsAre desired for bird huntersShoot a large number of small pellets that disperse in a circular patternHave a butt stock and a long barrel, but lack rifling inside the barrelThe diameter of the barrel is expressed as a gaugeA higher gauge means a smaller barrel and less kinetic energyShotgunsCommercially Available version: singe-shot, double-barrel, bolt-action, pump-action, and semiautomatic modelsSawed-off shotguns: created by cutting down the barrel and the stockAre easier to concealDeliver more damage per shot at close range, but are less effective over long distanceAmmuntitionBullets: designed with an aerodynamic shape that has a parabolic front and a wind-splitting shapeCartridges: consists of a brass case that contains a primer, gunpowder, and a bulletShotgun shells: May contain a bore-size projectile (slug), pellets of a large shot, or many tiny pellets