Letter P

The Definition of Port

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Port

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


19 Other Firearms Definitions You Need To Know


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.

Magnum

From the Latin for "more." A term indicating a relatively heavily loaded metallic cartridge or shotshell and a gun safely constructed to fire it. It generally indicates a round which cannot be interchanged with other loadings of the same caliber (for example, a .22 Magnum shell does not fit within a firearm designed to fire .22 Long Rifle ammunition).

Snap Caps

Dummy cartridges with spring-loaded "primers" used to test the mechanical functioning of a firearm, particularly the trigger pulls, hammer-fall and ejector-timing of a break-open gun. It is not advisable to dry-fire a break-open gun on an empty chamber. Hardened steel parts can shatter without the soft brass primer to act as a shock absorber. Snap caps cushion the blow of the hammer and firing-pin when the use of a live cartridge would be impractical.

Firepower

A volume of fire delivered by a military unit. Incorrectly used by the media to mean the ability of a small arm to be discharged many times without reloading.

Ballistics

The science of cartridge discharge and the bullet's flight. Internal ballistics deals with what happens inside of a firearm upon discharge. External ballistics is the study of a projectile's flight, and terminal ballistics is the study of the impact of a projectile.

Doglock

The lock that preceded the 'true' flintlock in both rifles and pistols in the 17th century. Commonly used throughout Europe in the 1600s, it gained popular favor in the British and Dutch military. A doglock carbine was the principal weapon of the harquebusier, the most numerous type of cavalry in the armies of Thirty Years War and the English Civil War era.

Trigger Break

The point at which the trigger allows the hammer to fall, or releases the striker, so that the shot fires. The ideal trigger break is sudden and definite. "Like a glass rod" is the cliche term shooters use to describe the ideal crisp, clean break.

Saturday Night Special

A slang term for a small inexpensive handgun. Saturday night specials have been defined as compact, inexpensive, small-caliber handguns with perceived low quality; however, there is no official definition of "Saturday night special" under federal law, though some states define "Saturday night specials" or "junk guns" by means of composition or materials strength. Low cost and high availability make these weapons attractive to many buyers despite their shortcomings.

Lands

In the rifling of a bore, the uncut portions of the barrel's inner surface left after the rifling grooves have been cut into the metal. In other words, the raised portion of rifling.

Wound Trauma Incapacitation

The correct technical term for the ability of a projectile to incapacitate an animal or human shot with a firearm. Incorrectly called Stopping Power.

Adjustable Trigger

A trigger that can be easily adjusted by the user. Adjustable triggers are common on specialized target-shooting firearms.

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.

Bore Diameter

The measurement from one side of the bore to the other. In a rifled barrel this means measurement of the bore before the rifling grooves are cut.

Firearm

A firearm is a portable gun (pistol or rifle), being a barreled weapon that launches one or more projectiles often driven by the action of an explosive force.

Speed Loader

A device used to load magazines or revolver cylinders quicker than by hand.

Percussion Cap

A small metal explosive-filled cup which is placed over the nipple of a percussion firearm. As the cap is struck by the hammer, it explodes and sends a flame through the flashhole in the nipple to the main powder charge.

Express Sights

"V" shaped rear leaf sights mounted to a rifle barrel on a block or on a quarter-rib, sometimes solid standing, sometimes folding, and often mounted in a row of similar leaves, each of a slightly different height, marked with the range for which each is regulated

Obturation

The process of a bullet expanding under pressure to fit the bore of the firearm, or a cartridge case expanding under pressure to seal the chamber.

Closed Bolt Firing System

A type of firearm in which the action is closed, with a cartridge in the chamber prior to firing. When the trigger is pressed the cartridge is fired, and the action cycles loading another cartridge into chamber and when firing is stopped the bolt remains closed and the chamber remains loaded.