SCANLON SCIENCE



center27540900Unit 8: Firearms & BallisticsBy the end of this unit, you will be able to:Explain the differences between a handgun, a rifle, and a shotgunDescribe the rifling on a gun barrel and how it affects the flight of the projectileExplain barrel size and caliberDescribe how bullets are test fired and matchedDiscuss the role of ballistics recovery and examination at a crime sceneDetermine the position of the shooter based on bullet trajectoryUnit Vocabulary:Cartridge: ____________________________________________________________________Muzzle: _______________________________________________________________________Groove_______________________________________________________________________Land (ridges): ________________________________________________________________Caliber: ______________________________________________________________________Gunshot residue (GSR): ________________________________________________________Trajectory: ___________________________________________________________________IntroductionBallistic evidence helps explain: What __________________________________ was used The ______________ of the bullet The _____________ of bullets fired _____________ the shooter was _____________________ Whether a weapon was fired ____________________ If a firearm was used in _________________________________ 38246057112000History of Gunpowder and Firearms______________________ invented gunpowder over a thousand years ago 4056380-254000Muzzle – loading matchlocks used wicks to ignite the gunpowderFlintlock weapons used a spark from a chip of flintPercussion Firing Weapons______________________ - holds bullet, primer powder, gunpowder ______________________ hits primer powder which ________________ the gunpowder 325120021717000Breech loading is faster than muzzle loading.Long Guns and Handguns_______________________ Rifles fire bullets 450913533972500Shotguns fire pellets (_________) or a single projectile (__________) _____________________ Pistols are fired with _______________Revolvers have a cylinder that holds usually ________ cartridges __________________________ – 10 cartridges into a _____________________. Fires one bullet per pull of trigger 43567355080000___________________ – fires repeatedly as trigger is pulled Firearms and Rifling___________________________________ in the barrel of a gun produce the twisting that adds ___________________ This leaves a pattern on the bullet that is ________________ Bullets, Cartridge, and Caliber________________________—a case that holds a bullet, primer powder, and gunpowder 4509135000The bullet, usually of metal, is out front with the cartridge, holding the primer and propellant powders, behind. How a Firearm WorksThe firing pin hits the base of the ____________, igniting the ______________________________ The primer powder ______________ through the flash hole to the main propellant supply The _______________________________________ pushes the bullet from the casing into the barrel 27559037211000The bullet follows the ____________________________________ out of the barrel 4530725314642500Caliber of the Cartridge_____________________—a measure of the diameter of the cartridge In hundredths of an ______________ Common calibers include.22, .25, .357, .38, .44, and .45 Question: Why should the caliber of ammunition match the firearm that shoots it? If they do not match, what could go wrong? Discuss this this your neighbor! Write down your thoughts AND their thoughtsI think: __________________________________________________________ _________________________________________________________________My neighbor ________________ thinks: _____________________________ _________________________________________________________________The Study of Bullets a016954500nd Cartridge Casing3023235270891000Matching BulletsGun is “test-fired” into ______________________________. _________________________________ _________________________________ to suspect’s weapons, bullets, casings. Marks in the Spent Cartridge Casing ______________________________________Appear on the rim or center of the spent cartridge Can be used to match a cartridge to a firearm ______________________________________Produced when the cartridge casing slams backward and strikes the breechblock ______________________________________Only in semi-auto and automatic weapons Small scratches Gunshot Residues________________________________ (GSR) Particles of _____________________________ and traces of smoke 5537835-663321000Leave _______________ on the hand, arm, face, hair, or clothing of the shooter and/or victimChemical testing can detect residue _________________________________________ ____________________ from victim to shooter can be determined by examining the residue pattern on the victim Question: Do you think there is a relationship between the distance between the victim and shooter and the amount of gunshot residue? What do you think that relationship is? Discuss with your neighbor. _________________________________________________________________Bullet WoundsCan show what _________________________________ Was the victim running away? ________________ wounds are ____________ than exit wounds Skin stretches as bullet enters As bullet moves through the body it collects tissue _________________ may point in the direction the bullet moved ___________ found near entrance wounds ___________________ may burn skin if gun was close ___________________ bullets tend to remain _______________ in the body Trajectory18815054572000__________________ _________________ are needed to define the trajectory Investigators can figure the shooter discharged the firearm somewhere along that line Reference points can be Bullet holes in objects or victims An entry point and exit point on a victim Gunshot residue or spent cartridge casings ________________ can trace a straight-line path to determine the position of the shooter Trajectory and Gravity3711639-9206100Bullet’s path is slightly _____________ Gravity pulls it downward as the bullet moves forward Wind can affect trajectory Bullet can hit other objects and ricochet ................
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