Letter G

The Definition of Gas Check

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Gas Check

A metal cup placed on the end of a lead bullet to protect the lead against the hot gases of the burning powder charge. Used in some types of firearms ammunition when non-jacketed bullets are used in high pressure cartridges, to prevent the buildup of lead in the barrel and aid in accuracy.


19 Other Firearms Definitions You Need To Know


Windage

The setting on the sights used to accommodate the wind or adjust for horizontal (side-to-side) errors in the alignment of the sights with the bore of the firearm.

Down Range

The area of a gun range where firearms are pointed when they are fired. The area of the range forward of the firing line.

Cylinder Drum

On a revolver, a spring activated device housed in the bottom of the frame beneath the cylinder that engages alignment notches in the cylinder. It stops the cylinder's rotation and holds it in place each time a chamber in the cylinder is in alignment with the barrel.

Receiver

The housing for a firearm's breech (portion of the barrel with chamber into which a cartridge or projectile is loaded) and firing mechanism. In semi-automatic handguns and revolvers, this part is typically called the frame.

Interrupted Thread

A screw with about half of its threading removed in longitudinal sections. Often used at the breech end of a takedown firearm's barrel. When the barrel's interrupted female threads are inserted into the receiver's complementary interrupted male threads, only a partial rotation is necessary for assembly rather than many full turns.

Muffs

Slang for Ear Muffs.

Flinch

To jerk a firearm off target inadvertently in the instant of firing in timid anticipation of recoil. Commonly caused by learning to shoot with a gun more powerful then they are ready for.

Cover Hold

Sometimes also known as cover-up hold. A sight picture of when the center of the target is completely covered by the front sight when the sights are properly aligned. Also see center hold and six o'clock hold.

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.

Shell Casing

A hollow, piece of metal (or plastic in the case of a shotgun shell) that is closed on one end except for a small hole which holds a primer. The open end holds the bullet. The hollow portion holds the powder. Together the assembled unit is called a cartridge.

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.

Winchester Short Magnum

More commonly known as WSM, it is a family of centerfire cartridges designed by Winchester Repeating Arms Company

BATFE

Abbreviation for the Bureau of Alcohol, Tobacco, Firearms and Explosives

Line Of Bore

An imaginary straight line through the centre of the bore of a firearm extending to infinity.

Folding Stock

A long gun stock that may be doubled over for conveniently compact storage.

FPS

Abbreviation for feet per second. A term used in expressing the velocity of a bullet.

Globe Sight

A front sight assembly, primarily for target rifles, consisting of a tube, housing interchangeable beads and blades. The tube guards against imperfect aiming due to sight pictures influenced by reflections.

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.

Bipod

Sometimes spelled Bi-Pod. A support device that is similar to a tripod or monopod, but with two legs. On firearms, bipods are commonly used on rifles to provide a forward rest and reduce motion. The bipod permits the operator to rest the weapon on the ground, a low wall, or other object, reducing operator fatigue and permitting increased accuracy.