Letter P

The Definition of Prime

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Prime

To prepare or charge a muzzle loader for firing.


19 Other Firearms Definitions You Need To Know


Falling Block

A type of action used primarily for single shot rifles whereby some kind of lever actuates a breechblock, moving it downwards in a vertical recess to expose the chamber. May have visible or enclosed hammer. For any given barrel length, it allows a shorter overall rifle length compared to a bolt action because no space is taken up by the forward-and-back cycling of the bolt. Most of the better British makers produced them in limited numbers around the turn of the last century, the Farquharson being the most iconic. Perhaps the best-known falling block action today is the Ruger No.1.

Forend Iron

The steel skeleton of the forend (above), into which any moving parts are fitted and which mates to and revolves about the action knuckle when the gun is opened.

Brass

The term used for the casing on modern rifle and pistol ammunition. It is usually made out of brass but can also be aluminum or steel. The casing on a shotgun shell is usually refered to as a hull

Handloading

The process of assembling cartridge case, bullet or shot, wads and primer to produce a complete cartridge with the use of hand tools in the interest of loading for firearms for which cartridges are not available, experimenting with loads to achieve better performance, or to save money. Not to be attempted without knowledgeable instruction and careful study of the process.

Belt Fed

A firearm, usually (but not always) a fully automatic rifle, that uses a ammunition on a belt rather than a magazine to store the rounds that will be loaded into the gun.

MOA

Abbreviation for Minute Of Angle

Necking Up

Expanding the neck of an existing cartridge to make it use a bullet of a different caliber. A typical process used in the creation of wildcat cartridges.

Thumbhole Stock

A rifle stock, with a sculptured throughole at the wrist for the thumb, said to be more ergonometric to hold than a traditional stock. Apart from being slower to mount, totally useless for a counter-dexterous person, it is so unmitigatedly graceless as to be beneath consideration.

WTI

Abbreviation for Wound Trauma Incapacitation.

Buckshot

A type of shotgun ammunition that uses medium-sized to large-sized pellets of .24" in diameter or greater, designed to be discharged in quantity from a shotgun. Generally the larger the pellets, the fewer of them there are in casing.

Scope Blocks

A pair of small dovetailed steel bases, screwed usually one to the barrel and one to the front receiver ring of a rifle, to accept mounts for target scopes such as the Unertl where the scope is allowed to move forward in the rings under the recoil of the rifle and which typically carry the windage and elevation adjustments in the mount.

Cartouche

A mark within a border, typically stamped into the wood, especially of an American military rifle. It shows the initials of the name of the accepting inspector and often, the date he accepted the firearm into service.

Luger

American name for the German "Parabellum" semiautomatic pistol introduced in 1900. The Parabellum was designed by Georg Luger, and based on the earlier Borchardt pistol. The official German military nomenclature was "Pistole '08" or "Po8." At first, it was chambered for the 7.65mm Parabellum round. Soon, it was modified to use the 9mm Parabellum cartridge, which is what most people refer to today when talking about a 9mm cartridge. "Luger" is now a trademark owned by the Stoeger Arms Co.

Scope

A magnifying tube through which the shooter may see the target and aim the firearm. Scopes contain a reticle, commonly in the shape of a cross, which must be properly centered upon the target for accurate aim.

Bolt Thrust

The amount of rearward force exerted by the propellant gases on the bolt or breech of a firearm action or breech when a projectile is fired. The applied force has both magnitude and direction, making it a vector quantity.

Holographic Weapon Sight

a non-magnifying gun sight that allows the user to look through a glass optical window and see a cross hair reticle image superimposed at a distance on the field of view. The hologram of the reticle is built into the window and is illuminated by a laser diode.

Wad

A felt, paper, cardboard or plastic disk that is used in a shotshell. Also in muzzle loading, a piece of cloth used to seal the bullet in the barrel. It's purpose and function is the same as a shotgun wad.

Headspace

The distance, or clearance, between the base of a chambered cartridge and the breech face (or bolt face) of a firearm. This is a critical dimension, particularly in high powered rifles. If there is too little headspace, the bolt will not close. If there is too much headspace the cartridge will not be properly supported in the chamber and the cartridge will expand upon firing and may rupture, blasting high-pressure gas into the action and possibly into the body of the shooter. Headspace should be .003" - .006" in a centerfire rifle. It can be checked with a set of "Go and No-Go" gauges specific to the calibre in question. (See below.) With a standard cartridge, the headspace is registered by the shoulder, with a belted cartridge, the headspace is registered by the forward edge of the belt.

Port

An opening. The ejection port is the opening in the side of a semi-auto from which spent cases are ejected.