PROPELLANT

In a firearm, the chemical composition which, when ignited by a primer, generates gas. The gas propels the projectile. Also called powder, gunpowder, smokeless powder, blackpowder.

PULL-THROUGH

A flexible device that is pulled through the barrel of a firearm to clean the barrel.

PUMP ACTION

An action in which a moveable fore-end is manually actuated in a motion generally parallel to the barrel. This motion is transmitted to a breech bolt assembly which performs all the functions for loading and extracting cartridges. This type of action is prevalent in shotguns and is found to a lesser extent in rifles.

PROJECTILE ROTATION

The spinning motion that is imparted to a projectile due to engagement with the rifling in the barrel of a firearm, as it is driven down the barrel. The rate of rotation is dependent upon the rate of twist of the rifling and the velocity. The barrel twist (left or right) determines the direction of the rotation.

PRESSURE DETERMINATION

The act of measuring the pressure generated in cartridges or shotshells contained in the chamber of a test barrel. See Pressure. See Average Pressure. See Pressure Barrel. See Chamber Pressure. See Pressure Curve.

PRESSURE CURVE

A graph of the relationship of chamber pressure to time or travel in a firearm when a cartridge or shell is fired.

PRESSURE BARREL

A barrel, typically heavy-walled, made in accordance with a standards-setting organization specifications, with appropriate features for the installation of instrumentation to measure pressure.

PRESSURE

In a gun or cartridge, the force imparted to various components that is developed by the expanding gases generated by the deflagration of the propellant when fired.

PRESCRIBED LOAD

For every caliber of metallic cartridge and the numerous bullet weights used in each, and for each shotshell gauge or bore, and the various shot weights loaded in each, a particular combination of components should be used. Collectively, the correct components for any given cartridge or shell may be referred to as the prescribed load.