Originally in the Militech M-31a1 Advanced Infantry Combat Weapon and Militech-10 Submachine Gun available in 4 grenade magazine pump action or 16 grenade drum firing models. Drum model allows the user to choose which type of grenade they are firing(if they have multiple types loaded) Both types can also use 10 gauge shotgun ammo. Range of fire drops to 1 is changing grenade types between firing.