Letter: R

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.

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

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

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

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 projectile with spiral features and a hollow base, intended for use in smoothbore shotguns.

A firearm having spiral features in the bore to impart spin to a single projectile and designed to be fired from the shoulder.

The glancing rebound of a projectile after impact.

The protrusion of a rib beyond the breech end of a barrel.

A raised surface used as a sighting plane. Ribs may be either solid or ventilated. See Ventilated Rib.