Letter O

The Definition of Overbore Capacity

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Overbore Capacity

Is that combination of caliber, barrel length, bullet weight, and case volume which does not allow the complete burning of the charge of ballistically correct powder within the volume of case and barrel.


19 Other Firearms Definitions You Need To Know


Telescopic Sight

An optical sight, offering some magnification, often variable, with some kind of adjustable aiming grid inside (a reticle), which when mounted on a firearm, usually a rifle, makes sighting easier.

Mortar

An artillery piece used to fire shells over short ranges at very high trajectories.

Pump Action

A type of mechanism for removing a spent shell casing from the chamber of a firearm and inserting a fresh cartridge into the chamber. This type of mechanism is most commonly used in shotguns and rimfire rifles.

Gape

The degree to which the barrel(s) of a break-open gun drop down; the size of the opening space, which should be sufficient to allow for ease of loading, unloading and properly-functioning ejection. A good gape is easier to achieve on a side-by-side than an over & under where the bottom barrel is well-enclosed by the action body.

Rimless

A cartridge in which the base diameter is the same as the body diameter. The casing will normally have an extraction groove machined around it near the base, creating a "rim" at the base that is the same diameter as the body diameter.

Short Recoil

A semi-automatic pistol in which the barrel and breechblock are locked together for only a short distance of rearward recoil travel, at which point the two are uncoupled, the barrel is stopped and the breechblock continues rearward, extracting the spent casing from the chamber. Upon returning forward, the breechblock chambers a fresh round and forces the barrel back into its forward position. Most modern recoil operated semi-automatic pistols use short recoil.

Centerfire (Center Fire)

A cartridge with its primer located in the center of the base of the case.

Slide Lever

A slang term for slide catch.

Frangible

A bullet that is designed to disintegrate into tiny particles upon impact to minimize their penetration for reasons of range safety, to limit environmental impact, or to limit the danger behind the intended target. Examples are the Glaser Safety Slug and the breaching round.

Parabellum

Latin word meaning "for war." It is actually the proper name of the semiautomatic pistol commonly known in the USA as the "Luger. Because of that pistol and the ammunition created for it, the common 9mm cartridge used nowadays is also known as 9mm Parabellum or 9mm Luger."

AK

AK stands for Avtomat Kalashnikova (Kalashnikov rifle when translated into English). When someone says "an AK" they are usually referring to the AK-47 rifle which was originally designed in Russia by Mikhail Kalashnikov.

Single Action

An action type that when the trigger is pulled, the only thing the trigger does is drop the hammer (or striker). This applies to both revolvers, semi-automatic and automatic guns. On a single action revolver, the gun must be manually cocked before it can be fired. With semi-automatic and automatic guns that are single action, the only thing the trigger does is drop the hammer, striker or firing pin onto the cartridge. Then the firearm is cocked again when from the recoil of the fired round. A firearm that the gun is cocked and the hammer drops when the trigger is pulled is a double action gun.

Prime

To prepare or charge a muzzle loader for firing.

Sawed-Off Shotgun

Common term for federally restricted "short-barreled shotgun (rifle)" as with a conventional shotgun with barrel less than 18" (rifle less than 16") or overall length less than 26.

Overbore Ammunition

Small caliber bullets being used in large cases. E.g. .22 bullet in a .45 acp case.

Every Day Carry

Term used for a firearm that a person uses as their usual daily carry gun. It is also used to describe a gun that is good for carrying concealed on a regular basis. Factors for determining an EDC may include caliber, physical size, number of rounds, accuracy and/or other factors.

Barrel

A tube, usually metal, through which a controlled explosion or rapid expansion of gases are released in order to propel a projectile out of the end at a high velocity. It is the tube through which the bullet or shot travels. The barrel serves the purpose of providing direction and velocity to the bullet.

Crosshairs

The cross-shaped object seen in the center of a firearm scope. Its more-proper name is reticle.

Snubby

Slang word for short barreled revolver.