Prototype weapon designed at the request of the US Marine corps. The weapon is designed to fire from an open bolt when the selector lever is set on auto (for cooling) and from a closed bolt (for accuracy) when set on semi.

(In an "open bolt" weapon - such as machine guns, and most submachine guns - when the weapon is cocked, the bolt stays to the rear and is only released by the operation of the trigger to shoot. The bolt is held to the rear when the shooter releases the trigger or the weapon is out of ammo.

On a "closed bolt" weapon, as used in virtually all civilian semi autos and military assault rifles, the bolt is always in the closed (forward) position for firing).