Firearm Glossary

Caliber in small arms, the internal diameter of a firearm's barrel or a cartridge's bullet, usually expressed in millimeters or hundredths of an inch; in measuring rifled barrels this may be measured across the lands or grooves or; a specific cartridge for which a firearm is chambered, such as .44 Magnum. In artillery, the length of the barrel expressed in terms of the internal diameter.

Carbine is a shortened version of a service rifle, often chambered in a less potent cartridge or; a shortened version of the infantryman's musket or rifle suited for use by cavalry.

cartridge: the assembly consisting of a bullet, gunpowder, shell casing, and primer. When counting, it is referred to as a "round".

centerfire: a cartridge in which the primer is located in the center of the cartridge case head. Unlike rimfire cartridges, the primer is a separate and replaceable component. The centerfire cartridge has replaced the rimfire in all but the smallest cartridge sizes. Except for low-powered .22 and .17 caliber cartridges, and a handful of antiques, all modern pistol, rifle, and shotgun ammunition are centerfire.

chamber: the portion of the barrel or firing cylinder in which the cartridge is inserted prior to being fired. Rifles and pistols generally have a single chamber in their barrels, while revolvers have multiple chambers in their cylinders and no chamber in their barrel.

chambering: inserting a round into the chamber, either manually or through the action of the weapon.

choke: a tapered constriction of a shotgun barrel's bore at the muzzle end. Chokes are almost always used with modern hunting and target shotguns, to improve performance

clip: a device that is used to store multiple rounds of ammunition together as a unit, ready for insertion into the magazine of a repeating firearm. This speeds up the process of loading and reloading the firearm as several rounds can be loaded at once, rather than one round being loaded at a time.

COL (cartridge overall length): This is the maximum overall length the cartridge can be – and – expected to function properly in magazines and the mag well of a bolt-action rifle.

CQB: close-quarters combat or close quarters battle is a type of fighting in which small units engage the enemy with personal weapons at very short range, potentially to the point of hand-to-hand combat or fighting with hand weapons such as swords or knives.