This article is about a shotgun. For the security key, see master key.

The Masterkey is a door breaching

Door breaching

Door breaching is a process used by military, police, or emergency services to force open closed and/or locked doors. A wide range of methods are available, one or more of which may be used in any given situation...

 shotgun

Shotgun

A shotgun is a firearm that is usually designed to be fired from the shoulder, which uses the energy of a fixed shell to fire a number of small spherical pellets called shot, or a solid projectile called a slug...

 system manufactured by Knight's Armament Company

Knight's Armament Company

Knight's Armament Company is an American firearms and firearms parts manufacturer.It is owned by C. Reed Knight and based in Titusville, Florida. KAC is best known for producing the Rail Interface System and the Rail Adapter System grips for military firearms...

.

The Masterkey project was initiated during the 1980s to provide assault rifle

Assault rifle

An assault rifle is a selective fire rifle that uses an intermediate cartridge and a detachable magazine. Assault rifles are the standard infantry weapons in most modern armies...

s with a potent built-in door breaching tool. Individual soldiers were often forced to carry a breaching shotgun in addition to their standard issue rifle, but the Masterkey removes this need. The system consists of a Remington 870

Remington 870

The Remington Model 870 is a U.S.-made pump-action shotgun manufactured by Remington Arms Company, Inc. It is widely used by the public for sport shooting, hunting, and self-defense. It is also commonly used by law enforcement and military organizations worldwide.-Development:The Remington 870 was...

 12 gauge

Gauge (bore diameter)

The gauge of a firearm is a unit of measurement used to express the diameter of the barrel. Gauge is determined from the weight of a solid sphere of lead that will fit the bore of the firearm, and is expressed as the multiplicative inverse of the sphere's weight as a fraction of a pound . Thus...

 pump-action

Pump-action

A pump-action rifle or shotgun is one in which the handgrip can be pumped back and forth in order to eject a spent round of ammunition and to chamber a fresh one. It is much faster than a bolt-action and somewhat faster than a lever-action, as it does not require the trigger hand to be removed from...

 shotgun mounted on a M16

M16 rifle

The M16 is the United States military designation for the AR-15 rifle adapted for both semi-automatic and full-automatic fire. Colt purchased the rights to the AR-15 from ArmaLite, and currently uses that designation only for semi-automatic versions of the rifle. The M16 fires the 5.56×45mm NATO...

 or M4

M4 Carbine

The M4 carbine is a family of firearms tracing its lineage back to earlier carbine versions of the M16, all based on the original AR-15 designed by Eugene Stoner and made by ArmaLite. It is a shorter and lighter variant of the M16A2 assault rifle, with 80% parts commonality.It is a gas-operated,...

 assault rifle in an underbarrel configuration, much like the M203

M203 grenade launcher

The M203 is a single shot 40 mm grenade launcher designed to attach to a rifle. It uses the same rounds as the older M79 break-action grenade launcher, which utilize the High-Low Propulsion System to keep recoil forces low. Though versatile, and compatible with many rifle models, the M203 was...

 grenade launcher. It has a 3-round internal magazine and can carry a fourth round in the chamber.

The shotgun cannot be operated independently because it has no grip behind the trigger - when firing the Masterkey, the M16's magazine must be used as a makeshift pistol grip. Independent stocks and grips for the 870 are available for use, but they are incompatible with the M16 barrel mount. KAC makes an independent stock for the Masterkey that also can be used with the M203 grenade launcher.

The Masterkey inspired the M26 Modular Accessory Shotgun System, an attachable shotgun in use with the United States armed forces

United States armed forces

The United States Armed Forces are the military forces of the United States. They consist of the Army, Navy, Marine Corps, Air Force, and Coast Guard.The United States has a strong tradition of civilian control of the military...

.

See also

• Ciener Ultimate Over/Under
  Ciener Ultimate Over/Under
  The Ciener Ultimate Over/Under system is a modification of the Remington 870 by Johnathan Arthur Ciener. It is identical in purpose to the Knight's Armament Company Masterkey or the accessory weapon configuration of the Remington 870 MPS....
  
  
• Combat Shotgun
  Combat shotgun
  A combat shotgun is a shotgun that is intended for use in an offensive role, typically by a military force. The earliest shotguns specifically designed for combat were the trench guns or trench shotguns issued in World War I...
  
  
• M26 MASS