Firearms

To analyze the different rifling and grooves left on a bullet.

continues to fire as long as its trigger is depressed and ammunition is available

fires and reloads itself before firing another shot; a self-loading weapon

blow-back recoil gas piston

fired cartridge blows back against the breechblock, forcing it to the rear and extracting and ejecting the expended cartridge casing

the barrel of the weapon and its breechblock recoil a short distance together

gas forces piston to the rear; rod connects the piston to the breechblock so that the breechblock is also pushed to the rear

Cartridges are held in firing chambers in a rotating cylinder single action- fired by manually cocking the hammer and then pulling the trigger Double action- fired by a long trigger pull that raises the hammer, indexes a firing chamber under the hammer, and then allows the hammer to drop, firing the cartridge

fired by a long trigger pull that raises the hammer, indexes a firing chamber under the hammer, and then allows the hammer to drop, firing the cartridge

fired by manually cocking the hammer and then pulling the trigger

• cartridge is chambered in the pistol; simultaneously the firing mechanism is cocked • shooter pulls trigger, firing cartridge • some energy produced by the fired cartridge is used to move the slide or breechblock to the rear • spring compressed by the rearward travel of the slide or breechblock

Lever below the weapon’s receiver is dropped to move the breechblock to move the breechblock to the rear and cock the firing mechanism Raising the lever chambers a fresh round

AKA- slide action A slide under the barrel is moved to the rear to extract and eject the expended cartridge and cock the firing mechanism; pushing the slides forward chambers a fresh round

Expended cartridge is extracted and ejected by drawing the bolt to the rear; moving the bolt forward strips a fresh cartridge from a magazine and inserts it into the chamber

world-leading trade fair for hunting, shooting sports, equipment for outdoor activities and for civilian and official security

raised portions of the rifling are the lands and the recessed portions are the grooves

hills and valleys provides a better gas seal in relatively large diameter bores produced by hammer forging the barrel around a mandrel containing reverse impression of the rifling

the diameter of a shotgun’s bore. The gauge is calculated by determining how many lead balls of the same diameter as the bore would weigh one pound

propellant composed of nitrocellulose (single-base) or nitrocellulose plus nitroglycerin (double-base powders)

the original gunpowder, composed of charcoal, saltpeter, and sulfur, now used chiefly in antique firearms and in fireworks

National integrated ballistic information network national database of digital images of spent bullets and cartridge cases that were found at crime scenes or test fired from confiscated weapons Bureau ATF manages the system and provides the equipment to crime labs around the country.

National firearms examiner academy in Beltsville, Maryland Invetigators learn to match bullets to firearms, restore obscured or removed serial numbers, and to study crime scene reconstruction

3 possible outcomes • hypothesis is supported by the data indicating it is possible • hypothesis is rejected and excluded as a possibility • data is inconclusive

Organization of Scientific Area Committees (OSAC) Firearms and toolmarks subcommittee