vickers-maxim automatic machine gun

from the GNU version of the Collaborative International Dictionary of English.

• An automatic machine gun in which the mechanism is worked by the recoil, assisted by the pressure of gases from the muzzle, which expand in a gas chamber against a disk attached to the end of the barrel, thus moving the latter to the rear with increased recoil, and against the front wall of the gas chamber, checking the recoil of the system.