Letter: B

The interior of a barrel forward of the chamber.

A theoretical line through the center of the bore.

A brush used to clean the interior surface of the barrel of a firearm.

The pouring of a special alloy or material that has a low melting point and exceptional dimensional stability into the bore or chamber of a firearm. The cast is used to study physical characteristics of the bore.

A notch, usually in the hammer, in which the sear or trigger is held under tension of the mainspring until released by movement of the trigger or hammer. See Half Cock. See Full Cock.

An ignition component consisting of a cup, explosive mixture and covering foil. The anvil is an integral part of the cartridge case head in the bottom center of the primer pocket. One or more flash holes are drilled or pierced through the bottom of the primer pocket into the propellant cavity of the base. Commonly found in European cartridges.

A type of projection found mainly on top-break action gun designs. The bifurcated or divided projections are mounted on each side of the barrel (or lower barrel in over/under designs) and engage trunnions located on the receiver wall. This serves to reduce the overall height of the receiver-barrel assembly.

A non-technical term generally referring any firearm using a centerfire rifle cartridge with a bullet .30” or larger in diameter.

For target matches in the United States, cartridges utilizing bullets 0.300” in diameter or larger.

The divergence of shot pellets caused by collisions of pellets in the shot string as it comes into contact with the target.