A door-breaching shotgun manufactured as a custom part by Knight's Armament Company. Can be mounted under the barrel on a M4 or M16 assault rifle, like a M203 grenade launcher.
The Masterkey project was initiated during the 1980s to provide assault rifles with a potent built-in door breaching tool.
by Kaiveran October 06, 2008
The Masterkey is a combination weapon featuring an M4 attached to a Winchester 12 gauge shotgun. It is named Masterkey for its common use as a door remover.
Have a locked door? Not anymore.
by Detranova July 29, 2003