Letter O

The Definition of Off Hand

Arsenal Exchange - Firearms Classifieds - Industry Directory

Off Hand

To shoot while standing and without bracing against anything. Sometimes it can also mean to shoot with your non-dominant hand.


19 Other Firearms Definitions You Need To Know


Trapdoor

As in Trapdoor buttplate or Trapdoor Pistol Grip Cap, one of these articles of furniture including a hinged plate, covering a small compartment below in which may be stored several extra cartridges, sight bits, extra springs or pins, cleaning rod, etc.

Group

A set of holes in a target left by a succession of bullets fired from the same rifle or handgun, using the same ammunition and sight setting. Fired (within the limits of one's marksmanship ability) to determine the inherent accuracy of the rifle/ammunition combination, and to aid in the proper adjustment of the sights.

Velocity

The speed at which a projectile travels. Velocity is usually measured in feet per second or metres per second.

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.

Ambi

Short for the word Ambidextrous. Meaning that a feature of a firearms can be used by either hand, for example ambi-safety, ambi slide catch or ambi mag release.

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.

Peep Sight

An alternate name for Aperture Sight.

Hammer Bite

The action of an external hammer pinching or poking the web of the operator's shooting hand between the thumb and fore-finger when the gun is fired.

Centerfire (Center Fire)

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

Bolt Face

The forward end of the bolt which supports the base of the cartridge and contains the firing pin.

Cocked

A state of readiness of a firearm. The hammer (or similar mechanism if there is no hammer) only needs to be released by the trigger to cause the gun to fire.

Brick

A box of ammunition roughly equal in size and weight to a brick. Most often used to describe a 500-round container of .22 Long Rifle ammunition.

Magazine Disconnect

Another term for Magazine Safety

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.

Topstrap

The part of a revolver's frame connecting the recoil shield to the barrel-mounting recess; adding considerable strength compared to that of early black powder Colt revolvers, and providing a base for a rear sight.

Fixed Ammunition

A complete cartridge of several obsolete types and of today's rimfire and center-fire versions

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.

Twist

The length, within a rifled barrel, required to accomplish one full rotation. 1:12 Twist, means a bullet passing down the bore would complete one revolution in twelve inches. 1:7 Twist, means a bullet passing down the bore would complete one revolution in seven inches, which makes it a tighter twist than 1:12. Different weights of bullet require appropriate rates of twist.

Timing

The proper adjustment of the various interrelated moving parts of a gun so that every operation works in proper sequence, such as that the two ejectors of a double gun kick out the spent cases at the same instant and with the same force.