Firearm Glossary

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

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

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.

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.

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

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.

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.

burst mode: a firing mode enabling the shooter to fire a predetermined number of rounds with a single pull of the trigger.

buffer: component that reduces the velocity of recoiling parts (such as the bolt).

break-action: A firearm whose barrels are hinged, and rotate perpendicular to the bore axis to expose the breech and allow loading and unloading of ammunition.

brass: The empty cartridge case.

boresight: Crude adjustments made to an optical firearm sight, or iron sights, to align the firearm barrel and sights. This method is usually used to pre-align the sights, which makes zeroing (zero drop at XX distance) much faster.

bore snake: A tool used to clean the barrel of a gun.

bolt action: A type of firearm action in which the firearm's bolt is operated manually by the opening and closing of the breech (barrel) with a small handle. As the handle is operated, the bolt is unlocked, the breech is opened, the spent shell casing is withdrawn and ejected, the firing pin is cocked, and finally a new round/shell (if available) is placed into the breech and the bolt closed.

bluing or blueing: A passivation process in which steel is partially protected against rust, and is named after the blue-black appearance of the resulting protective finish. True gun bluing is an electrochemical conversion coating resulting from an oxidizing chemical reaction with iron on the surface selectively forming magnetite (Fe3O4), the black oxide of iron, which occupies the same volume as metallic iron. Bluing is most commonly used by gun manufacturers, gunsmiths and gun owners to improve the cosmetic appearance of, and provide a measure of corrosion resistance to, their firearms.