By U.S. Army definition, a selective-fire rifle chambered for a cartridge of intermediate power. If applied to any semi-automatic firearm regardless of its cosmetic similarity to a true assault rifle, the term is incorrect.

Any weapon used in an assault (see WEAPON).

A firearm designed to feed cartridges, fire them, eject their empty cases and repeat this cycle as long as the trigger is depressed and cartridges remain in the feed system. Examples: machine guns, submachine guns, selective-fire rifles, including true assault rifles.

A term used often to describe what is actually a semi-automatic pistol. It is, technically, a misnomer but a near-century of use has legitimized it, and its use confuses only the novice.

Originally a spherical projectile, now generally a fully jacketed bullet of cylindrical profile with round or pointed nose. Most commonly used in military terminology.

The earliest type of firearms propellant that has generally been replaced by smokeless powder except for use in muzzleloaders and older breechloading guns that demand its lower pressure levels.

A round loaded with blackpowder or a special smokeless powder but lacking a projectile. Used mainly in starting races, theatrical productions, troop exercises and in training dogs.

A gun mechanism activated by manual operation of the breechblock that resembles a common door bolt.

The interior of a firearm's barrel excluding the chamber.

A synonym for expended metallic cartridge cases.