Letter: A

A code number and/or letter(s) usually found on the carton that identifies a particular quantity of ammunition for its manufacturer.

1) A projectile designed to penetrate armor.
2) A regulatory term applied to projectiles based solely on their composition and construction details, regardless of actual ability to penetrate armor.

A firearm design that continuously feeds cartridges, fires and ejects cartridge cases as long as the trigger is fully depressed and there are cartridges available in the feed system. Actuation of the mechanism may be from an internal power source such as gas pressure or recoil, or external power source, such as electricity.

A device in break-open firearms which expels fired cases when the action is opened.

A system for reloading a firearm utilizing some of the energy realized from firing a cartridge.

A common but improperly used term applied to autoloading pistols in use today. Most current “automatic” pistols are truly semiautomatic in action only. See Semiautomatic.

A fully automatic shoulder firearm that starts firing when the trigger is pulled and continues until the trigger is released or ammunition is exhausted. The term should not be used in conjunction with semiautomatic firearms. See Semiautomatic.

A safety device on some firearms intended to return to the On position when the action is opened.

An adapter that, when installed in a gun chamber for which it was designed, permits a smaller cartridge to be fired in the gun.

The arithmetic mean of pressure measurements for a number of rounds in a single test.