Letter T

The Definition of Throat Erosion

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Throat Erosion

The wearing of the portion of the barrel where the gas pressure and heat is highest as the projectile leaves the chamber. The greater the chamber pressure the more rapid throat erosion occurs which is compounded by rapid firing which heats and weakens the steel.


19 Other Firearms Definitions You Need To Know


Recoil

The tendency of a firearm when fired to move backwards, and a little upwards as a reaction to the force of the projectile moving down the barrel. As Newton says, to every action there is always an equal and opposite reaction. The mass of the firearm provides some inertia to counteract the momentum of recoil. What remains is absorbed by at the shoulder or the hand. The heavier the gun, the less the recoil. The more powerful the cartridge, the more the recoil.

Cal

Abbreviation for Caliber.

Bottlenecked (Bottle Necked)

A type of cartridge whose bullet diameter is substantially less than the body diameter of the casing.

Collateral Damage

Damage that is unintended or incidental to the intended outcome.

Magazine Pouch

Commonly shortened to mag pouch, this is a device to hold extra magazines which fastens to the shooter's belt.

Sabot

An oversized, lightweight housing that allows a sub-calibre projectile to be fired in a larger-diameter bore, usually in the interest of increased velocity. The sabot falls away from the actual projectile upon exiting the muzzle. For example, a hunter could use his .30-30 deer rifle to shoot small game with .22 centerfire bullets.

BB

A type of steel round shot fired from air rifles. The name originated from the size of steel balls used in a shotgun of the same size (.177 caliber). In a 12 guage shotgun shell using BB size shot, there will be typically 90 BBs in a shell

Handgun

Synonymous with pistol. A small, short-barreled firearm designed to be fired while held in one or both hands, possibly small enough to be concealed on the person, rather than while braced against the shoulder. The term includes antique dueling pistols, modern single-shot, semi-automatic pistols and revolvers.

Boattail

The tapered rear end of a bullet. This design is used to increase ballistic efficiency at long range.

Parallax

This occurs in telescopic sights when the primary image of the objective lens does not coincide with the reticle.Telescopic sights often have parallax adjustments to minimize this effect.

NRA

The National Rifle Association. This organization coordinates shooting events on a national level, provides firearms training to civilians and law enforcement, fights restrictive firearms legislation and supports the constitutional right of law abiding citizens to own and carry firearms.

Tangent Sight

A style of rear sight, typically used on rifles for either slow-moving bullets or for long ranges, whereby a ladder may be raised from flush with the barrel to a vertical position, and which incorporates a sliding crossbar which may be moved vertically in order to achieve significant elevation.

Gunpowder

Also called black powder, gunpowder is a mixture of sulfur, charcoal, and potassium nitrate. It burns rapidly, producing a volume of hot gas made up of carbon dioxide, water, and nitrogen, and a solid residue of potassium sulfide. Because of its burning properties and the amount of heat and gas volume that it generates, gunpowder has been widely used as a propellant in firearms and as a pyrotechnic composition in fireworks. The term gunpowder also refers broadly to any propellant powder. Modern firearms do not use the traditional gunpowder (black powder) described here, but instead use smokeless powder.

Crosshairs

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

Rifle

A shoulder-fired long gun which has a rifled barrel.

Projectile

A bullet or shot in flight after discharge from a firearm.

Shell

An empty ammunition case.

Disc-Set Strikers

Circular steel fittings, about 1/2 inch in diameter, screwed into the breech face of a gun and through which the firing pins pass. Firing pin bushings allow the convenient replacement of broken firing pins. They also allow the renewal of an older gun where, over the decades, leakage of high-pressure gas from corrosive primers has eroded the breech face around the firing pins; and replacing these bushings with new ones, slightly oversized can compensate for a situation where proper headspace has been compromised.

Ballistic Coefficient

A measure of projectiles ability to overcome air resistance in flight. It is inversely proportional to the deceleration—a high number indicates a low deceleration. Ballistic Coefficient (abbreviated as BC) is a function of mass, diameter, and drag coefficient. In bullets it refers to the amount that drop over distance and wind drift will affect the bullet.