CFP

Abbreviation for Concealed Firearms Permit.

Breech Pressure

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. This is also known as Bolt Thrust on firearms that are Bolt Action

Double Rifle

Two independent rifles, built on one frame, designed to allow two virtually instantaneously quick, totally reliable shots. The barrels may be arranged either side-by-side or over-and-under. The apogee of the gunmaker's art. Particularly useful against dangerous game, which may be moving, and in your direction, with vengeance on its mind.

Double-Set Trigger

Usually only found on black powder muzzle loading rifles and pistols, pulling the rear (set) trigger converts the front (main) trigger to a light, hair trigger (too light and sensitive to be carried safely in the field). While the front trigger is always at the ready, if one has the time, using the set trigger feature may allow for a more accurate long-distance shot. Operates using its own miniature firing mechanism (sear, spring and hammer) when cocked, to multiply the force of a pull on the main trigger.

Mississippi Rifle

Nickname for the U.S. M1841 Rifle, a .54 caliber muzzleloading rifle. The name comes from their use by a group of U.S. Volunteers from Mississippi who were commanded by Jefferson Davis in the Mexican War. Some were later rebored to .58 caliber.

High-Capacity Magazine

An inexact, non-technical term indicating a magazine holding more rounds than might be considered "average.".

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.

Monoblock Barrels

A method of building a pair of barrels where the entire breech end of both barrels and the lumps together are machined from one solid piece of steel. The barrel tubes are then fitted separately into this monoblock and the ribs attached. Often identifiable by a distinctive ring around the barrels about three inches in front of the breech end. The favored jointing method of the Beretta company. An incorrect euphemism for sleeved barrels.

Youth Rifle

A short, lightweight rifle. Some are small enough for a young child to easily handle, while others are large enough to perfectly suit teenagers, average-sized adult women, and small-statured adult males.

Smooth Bore

A barrel without rifling. Smooth bore barrels are commonly used in shotguns and in large bore artillery that fire fin stabilized projectiles.

Hand

In any mechanism, a small lever that engages a notch to actuate movement in one direction only. Specifically, a small spring-loaded lever attached to the hammer of a revolver which actuates the cylinder to advance one increment and move the next chamber into battery as the hammer is cocked.

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.

Bore Snake

A bore snake is a tool used to clean the inside (bore) of the barrel of a gun. It resembles a short section of rope with a smaller, weighted cord attached to one end to help feed the bore snake through the barrel. A bore snake often has one or more integrated brushes to help clean the barrel, and may also be used to apply lubricant. It is an alternative to using a cleaning rod and patches to clean the barrel of a gun. Bore snakes are made in different sizes for different calibers and gauges of guns.

Detonate

To explode with great violence. It is generally associated with high explosives e.g. TNT, dynamite, etc., and not with the relatively slow-burning smokeless gunpowders that are classed as propellants.

Slamfire

A premature, unintended discharge of a firearm that occurs as a round is being loaded into the chamber.

Loading Gate

The hinged cover over the opening through which cartridges are inserted into the magazine.

Deterrent

A material added to an explosive to slow its burning rate.
Something that will prevent or hinder something from happening.

Cheekpiece

A broad, flat, raised area on the side of a buttstock.

ATF

Short abbreviation for the Bureau of Alcohol, Tobacco, Firearms and Explosives

Cartouche

A mark within a border, typically stamped into the wood, especially of an American military rifle. It shows the initials of the name of the accepting inspector and often, the date he accepted the firearm into service.