Letter I

The Definition of Interrupted Thread

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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.


19 Other Firearms Definitions You Need To Know


Ricochet

A rebound, bounce or skip off a surface, particularly in the case of a projectile.

Drift

The departure of a bullet or shot charge from the normal line of flight. This can be caused by wind or the unbalanced spinning of the bullet.

Heavy Machine Gun

A larger class of machine gun..

Thunder

With the execption of the BP model series, Thunder is the name of all of Bersa's pistols. The line currently consists of three frames.

• The Thunder .380 series, which is a very reliable and good looking compact blowback system .380 acp pistol (there is also a .22lr version).
• The full size Thunder Pro series (avalable in 9mm and .40 S&W) is a locked breech design.
• The Thunder Ultra Compact Pro series, locked breech, short recoil design which is more of a commander size Thunder Pro (available in 9mm, .40 S&W, and .45 acp).
The Bersa Thunders are well known among firearms enthusiasts for being extremely high quality guns at reasonable prices.

Spray and Pray

A term often used to refer to the very poor and dangerous practice of rapidly firing many shots at a target as possible in the hope that one or more may hit the target. This practice is a danger not only to bystanders but also to the shooter.

Ballistics

The science of cartridge discharge and the bullet's flight. Internal ballistics deals with what happens inside of a firearm upon discharge. External ballistics is the study of a projectile's flight, and terminal ballistics is the study of the impact of a projectile.

WCF

Abbreviation for Winchester Centerfire.

Keyhole

The tendency of a bullet to tip in flight and hit a target sideways, leaving a distinctly oblong hole. This destabilization of the spinning bullet in flight is typically caused by a bullet weight inappropriate for the rate of twist of the rifled barrel, an out-of-balance bullet or its having nicked an impediment such as a blade of grass, in flight.

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.

Action

The working mechanism of a firearm involved with presenting the cartridge for firing, and in removing the spent casing and introducing a fresh cartridge. For example some of the most common types of Actions are single, double, bolt, lever and pump.

Holster

A gun holder that may be strapped to a human body, or affixed to the inside of a pack or bag, or dropped into a pocket. A holster serves to protect the gun's mechanisms and finish, to provide security by covering the trigger so it cannot be pulled inadvertently, and to present the grip of the gun at a constant angle for easy access. Some holsters also serve to obscure the outline of the gun so it may be more easily concealed. Typically made from leather or in plastic.

Point of Aim

The point at which you are aiming the firearm at.

Armor-Piercing Ammunition

An armor-piercing shell must withstand the shock of punching through armor plating. Shells designed for this purpose have a greatly strengthened case with a specially hardened and shaped nose, and a much smaller bursting charge.

Throat

The beginning of the bore of a rifled firearm. The transition between the chamber and the rifling. The area most vulnerable to erosion from high velocity cartridges.

Cartridge

The assembly consisting of a bullet, gunpowder, shell casing, and primer. Cartridges also include shotgun shells and black powder packets used in muzzle loading guns.

Black Powder

Also known as Gun Powder. 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. Modern firearms do not use the traditional black powder described here, but instead use smokeless powder.

Night Sights

A type of iron sights that glow or shine in the dark, intended for use in low light conditions. Some night sights consist of tiny tubes of tritium, while others use a phosphorus paint.

Die

A piece of tooling used to form a sequence of uniform parts through the use of heat and/or pressure; especially, in firearms terminology used to form brass cartridge cases accurately to their correct size for reloading.

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.