The term "machinegun" as used in this chapter means any weapon which shoots, is designed to shoot, or can readily be restored to shoot, automatically more than one shot, without manual reloading, by a single function of the trigger. The term shall also include 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 a person. The term also includes any weapon deemed by the federal Bureau of Alcohol, Tobacco, and Firearms as readily convertible to a machinegun under Chapter 53 (commencing with Section 5801) of Title 26 of the United States Code.