20-millimetre (0.8-inch) weapon capable of firing at a rate of up to 7,200 rounds per minute. Such extremely rapid fire is thought necessary in combat between supersonic aircraft, for a target may only be in the gunsight for a second or less at one time.

To attain the requisite speed, six barrels are electrically fired and rotated in succession, an arrangement basically like that of the 19th-century Gatling gun. The Vulcan is widely used in aircraft and various tactical surface weapon systems.