Firearms and Toolmarks Flashcards
semi-automatic vs automatic firearms
semi-automatic = trigger fires one bullet at a time
automatic = trigger continuously fires (like a machine gun)
fireformed vs non-fireformed impressions
fireformed = can only occur if gun is fired
non-fireformed = can occur by simply loading cartridge into firearm
what are examples of non-fireformed impressions
extractor impression, ejector mark, magazine mark
extractor vs ejector
extractor = removes cartridge case from the chamber
ejector = expels cartridge case from gun
handgun vs long gun
handgun = one hand, no other support needed
long gun = two hands, shoulder, etc.
revolver vs pistol
revolver = revolving chamber
pistol = stationary chamber
rifle vs shotgun
rifle = single projectile
shotgun = cluster of pellets (sprays)
bolt action vs lever action vs pump
bolt action = pull forward and back on top of gun
lever action = pull lever out by trigger
pump action = pull forward and back on bottom of gun
single vs double action
single action = pull slide/cock hammer manually each time
double action = trigger cocks hammer for you
what does barrel rifling do?
allows bullet to fire straight
what are some class characteristics of rifling?
- caliber
- twist (R or L)
- number of lands or grooves
- width of lands and grooves
which way do the machining marks run for grooves? what about lands?
grooves = length of barrel (across)
lands = axis of barrel (up and down)
how do you find the caliber of rifling?
distance between the lands
what does the cartridge case contain?
primer, propellant, and bullet
what are cartridge cases usually made of?
brass (also use steel or aluminum)