Hot Range

A condition (status) of a shooting range that shooters may commence to fire.

Speed Loader

A device used to load magazines or revolver cylinders quicker than by hand.

Touch Hole

A small orifice at the breech end of the barrel of a muzzle-loading firearm through which the exploding priming charge is conducted from the flash pan to the main charge.

Muzzle

The open end of the barrel from which the projectile exits.

Headspace Gauge

Plugs of hardened steel, precisely machined in relation to the standard dimensional specifications of a given cartridge, normally in sets of three: "GO", "No-Go" and "Field". By loading these plug-gauges into the chamber in succession, one can check that the action should close on the "Go" gauge. It should not close on the "No-Go" gauge, but might were enough force to be used. And, it absolutely should not close on the "Field" gauge.

Six O'Clock Hold

A sight picture of when the center of the target rests on top of the front sight when the sights are properly aligned. Also see center hold and cover hold.

Intercepting Sear

A second sear, poised just behind a second notch in the hammer. It is possible that when a cocked firearm is dropped or sharply jarred, a single sear could jump out of its notch and the hammer could fall, firing the gun accidentally. In this event, an intercepting sear would engage before the hammer could fall completely, preventing an accidental discharge. On a gun with intercepting sears, only by pulling the trigger are both sears moved out of the way simultaneously, allowing the gun to fire. Intercepting sears are usually found on better sidelock actions. They are sometimes found on best boxlocks, and can be recognized by an extra screw behind the action fences, in addition to the usual two screws (or pins) along the lower rear of the receiver.

Rate of Fire

The frequency at which a firearm can fire its projectiles.

Match Grade

A higher quality item used to increase accuracy, generally used for competition in a match. Match grade ammo and barrels are the most common improvements made to a firearm to improve accuracy for competition.

Safe

A firearm is said to be on safe when its safety is engaged and off safe when it is ready to fire.

Primer

A small metal cup that contains a tiny explosive charge that is sensitive to impact. A primer is placed in the base of a shell casing to ignite the powder of the completed cartridge. It is detonated by the striking of a firing pin in the firearm.

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.

Igniting Charge

The charge used to ignite the propelling charge.

Cant

To tilt a gun to one side or the other, complicating sighting considerably. Can cause material loss of accuracy, particularly with a rifle at longer ranges. Some better long range target rifles are equipped with Spirit Level sights to help control canting.

Kentucky Rifle

Usually referred to as a Kentucky Long Rifle or simply Longrifle, the Kentucky Rifle is a flintlock rifle with a long barrel and short, crooked stock. It is widely believed to be a largely unique development of American rifles that was uncommon in European rifles of the same period. The Kentucky Long Rifleis an early example of a firearm using rifling, (spiral grooves in the bore). This gave the projectile, commonly a round lead ball, a spiraling motion, increasing the stability of the trajectory. Rifled firearms saw their first major combat usage in the American colonies during the Seven Years war, and later the American Revolution in the eighteenth century.

Boresight (Bore Sight)

Crude adjustments made to an optical firearm sight, or iron sights, to align the firearm barrel and sights. This method is usually used to pre-align the sights, which makes zeroing (zero drop at XX distance) much faster.

Deringer

The original small single-shot or multi-barreled pocket pistol designed and manufactured by Henry Deringer of Philadelphia. Derringers (spelled with two Rs) are called that because of the original desinger and anmufactuturer of that type of gun, Henry Deringer. To get around copyright infringment other designers and manufacturers spell the name with two Rs. However guns designed and built by Deringer are spelled with only one R

Shotgun

A smooth bore long gun that shoots a group of pellets called shot instead of bullets. Depending on the bore size and the size of the pellets there may be from less than 10 to two hundred or more pellets in a single shotgun cartridge. Shotguns are designed for shooting moving targets (such as flying birds or running rabbits) at close range.

Cast Off

An offset of a gun stock to the right, so that the line of sight aligns comfortably with the right eye while the butt of the stock rests comfortably on the right shoulder. Almost all right-handed shooters benefit from a little castoff and most custom built guns are made this way. The only question is how much. The castoff of a gun is about right when, with the gun comfortably mounted, the front bead lines up with the center of the standing breech.
A stock offset to the left, for shooting from the left shoulder is said to be

Racking the Slide

Pulling the slide back to its rearmost position, and then letting it go forward under its own spring tension. Racking the slide loads the chamber and prepares the gun to fire in a semi-automatic handgun.