 Metal Storm also introduced inductive electronic ignition of the propellant, effectively from outside the barrel.A minigun with a belt of separate firing chambers also exists.The Multi-shot Accessory Under-barrel Launcher (MAUL) is an electronically fired, 12-gauge shotgun for use as an accessory weapon to a range of weapons, such as the M4 or M16 rifle, or as a stand-alone 5 shot weapon, providing a range of lethal (buckshot and slug) and non-lethal (blunt impact, door breaching, and frangible) munitions, all preloaded in 5 round "stacked projectiles" munition tubes.