KAC Masterkey shotgun
Country of origin

United States


Knight's Armament Company


Knight's Armament Company

Year(s) designed


Weapon type



12 gauge

Overall length

43.2 cm (17.0 in)


2.6 kg (5.7 lb)

Magazine/Cylinder capacity

3+1 rounds, internal magazine

The KAC Masterkey is an under barrel 12 gauge pump-action shotgun system manufactured by Knight's Armament Company. It is intended as a breaching tool.

History Edit

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

Design Details Edit

The system consists of a shortened Remington 870 12 gauge shotgun, and is compatible with M16/M4 platform rifles in an underbarrel configuration (in a similar matter to how the M203 grenade launcher is affixed to the underside of said rifles' barrels). The Masterkey has an internal 3-round tubular magazine, and a round can be stored in the chamber, giving a maximum capacity of 4 shells.

Because the shotgun has no grip behind the trigger, standalone usage of the shotgun is very awkward. When firing the Masterkey, the main rifle's magazine substitutes as a makeshift pistol grip. An independent stock by KAC has been made for the Masterkey shotgun, and is also compatible with the M203.

The Masterkey influenced the M26 Modular Accessory Shotgun System (MASS), an underbarrel shotgun in use with the United States armed forces. The US Army chose the latter as their preferred breaching shotgun.

Trivia Edit

  • The name "Masterkey" implies that the shotgun can unlock, or in this case, destroy most standard locks to open doors.

References Edit