Archives: Glossary

Any type of spiral internal bore feature of the barrel wall that imparts spin on the projectile for the purpose of stabilizing it in flight. This may be a series of lands and grooves, polygonal, hexagonal, or other configurations.

A tool having a series of cutting edges of progressively increasing height used to cut the spiral features in a rifled barrel.

That part of the hook or cut rifling tooling that holds the cutter and the mechanism for deepening the cut as the operation progresses.

The distance the projectile must move along a rifled bore to make one revolution. Usually expressed as “one turn in x inches (or millimeters).”

The flanged portion of the head of a rimfire cartridge, certain types of centerfire rifle and revolver cartridges and shotshells. The flanged portion is usually larger in diameter than the cartridge or shotshell body diameter and provides a projecting lip for the firearm extractor to Engauge so that the cartridge or shotshell may be extracted from the chamber after firing. In a rimfire cartridge the rim provides a cavity into which the priming mixture is charged.

A counterbore in the rear end of a chamber or bolt face to support the head of a rimmed cartridge.

A rimmed cartridge design in which the rim is formed with a cavity to contain the priming mix.

A type of primer found in the circumferential cavity or rim of rimfire ammunition. Usable only with rimfire guns. See Centerfire Primer.

A centerfire cartridge whose case head is of the same diameter as the body and having a groove turned forward of the head to provide the extraction surface.

A cartridge having a rimmed or flanged head that is larger in diameter than the body of the case. May be either rimfire or centerfire.