Letter P

The Definition of Primer Pocket

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Primer Pocket

The counter bore in the center of the base of a centerfire cartridge casing in which the primer assembly is seated.


19 Other Firearms Definitions You Need To Know


Powder

The chemical propellant which is burned to produce the hot gases which send the projectile flying downrange.

Scout Rifle

A concept created by eminent gun writer Col. Jeff Cooper. A scout rifle, generally, is a bolt action carbine firing a medium power round suitable for taking large game (e.g., .308), fitted with a long eye-relief telescopic sight mounted on the barrel, and a back up set of iron sights.

Hornady Magnum Rimfire

A type rimfire rifle cartridge developed by the ammunition company Hornady. .17 Hornady Magnum Rimfire (4.527mmR), commonly known as the .17 HMR, was developed in 2002. It descended from the .22 Magnum by necking down the .22 Magnum case to take a .17 caliber (4.5 mm) bullet.

Caliber

The diameter of the bore of a firearm measured as a fraction of an inch. Although such a measurement may be frequently stated in millimeters. It is correctly expressed as ".40 caliber" (note the decimal point) or as "10 millimeter" (without "caliber" or the leading decimal point). Caliber numbers when used to identify the size of the bullet a gun will file are usually followed by words or letters to create the complete name of the cartridge. These letters often represent a brand name or an abbreviation for the name of the company that first introduced the round.

Mauser Safety

A small lever mounted to the cocking piece of a Mauser 98 action (and its copies such as the Springfield 1903), rotating on a longitudinal axis from left (Fire), up to the top (Safe, but allowing bolt movement), and over to the right (Bolt and firing pin locked Safe). While commendable for locking the firing pin instead of just the trigger, its up-and-over arc of operation requires a scope to be mounted awkwardly high. Paul Mauser is not to be blamed; when his safety was developed, telescopic sights were in such infancy as not to be worthy of mainstream consideration.

Open Frame

Refers to a revolver frame that has no top-strap over the cylinder.

External Safety

A safety lever or button found on the outer surfaces of the firearm and is accessible to the user. Enabling the external safety should prevent accidental pulling of the trigger. However, the best safety is always you.

Nipple

A small metal tube extending through the breech of a percussion firearm through which the flame passes from the percussion cap to fire the powder charge.

Bolt Action

A type of firearm action in which the guns's bolt is operated manually by the opening and closing of the breech (barrel) with a small handle. As the handle is operated, the bolt is unlocked, the breech is opened, the spent shell casing is withdrawn and ejected, the firing pin is cocked, and finally a new round/shell (if available) is placed into the breech and the bolt closed.

X-Bolt

A bolt-action designed by Browning firearms. The x-bolt action features a short 60° bolt lift. So it is fast cycling and allows working the bolt quicker without the scope getting in the way.

M1911

The official US military designation for the Colt .45 semiautomatic pistol adopted by the US in 1911. The gun was designed by John Moses Browning, and produced by Colt. During trials, the Browning-Colt design beat out several competing designs, including one from Savage and a .45 caliber version of the German Parabellum ("Luger"). The M1911 saw its first combat in the Philippines and then in World War I. Early use showed that it could be improved and in 1921 the M1911A1 was introduced, which featured a few changes like a reocontoured frame, shorter trigger, and a rounded backstrap. The M1911A1 remained the standard US military handgun until it was replaced in the 1980's by the Beretta M9. However, it remains very popular with civilian shooters in the US, and has been modified extensively to update it to conform to more modern theories of handgun usage.

Under Barrel

The bottom barrel on an Over/Under shotgun.

Internal Safety

A safety which is placed within the gun and is not accessible to the user. Internal safeties are generally designed to prevent unintentional discharges when the gun is dropped or mishandled.

Spray and Pray

A term often used to refer to the very poor and dangerous practice of rapidly firing many shots at a target as possible in the hope that one or more may hit the target. This practice is a danger not only to bystanders but also to the shooter.

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.

Model 70 Type Safety

A small lever mounted to the cocking piece of a Winchester Model 70 rifle, rotating on a vertical axis from front (Fire), halfway back (Safe, but allowing bolt movement), and fully back (Bolt and firing pin locked Safe). While, like the Mauser, commendable for locking the firing pin instead of just the trigger, its fore and aft movement is both easier to operate and it allows lower mounting of telescopic sights, reducing parallax between the line of sight and the line of the bore and increasing the range of distances for which the scope may be reliably sighted-in.

Toe

The bottom of the butt-end of a gun stock.

Firing Pin Block

A type of internal safety that prevents the firing pin from moving forward for any reason unless the trigger is pulled.

Energy

The amount of work done by a bullet, expressed in foot pounds.