The Double Tap Trigger Fires ONE round when the trigger is pulled and fires ONE round when the trigger is released.
The National Firearms Act defines "machinegun" as "any weapon which shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot, without manual reloading, by a single function of the trigger." 26 U.S.C. 5845(b). The term also includes "the frame or receiver of any such weapon, any part designed and intended solely and exclusively, or combination of parts designed and intended, for use in converting a weapon into a machinegun, and any combination of parts from which a machinegun can be assembled if such parts are in the possession or under the control of the person." Id.; see 18 U.S.C. 921(a)(23); 27 CFR 478.11, 479.11.