The right side-plate of a Vickers/Maxim-type firearm, manufactured with its camming lobe affixed in the proper location, and without an ATF approved block that prevents installation of machinegun fire control components, is a machinegun receiver, and therefore, a machinegun as defined by the GCA and NFA. Provided it has not been disassembled into its component parts, a complete Vickers/Maxim-type machinegun that is currently registered in the National Firearms Registration and Transfer Record with its serial number located on a component part of the receiver box other than the right side-plate has been lawfully registered under the NFA and may be lawfully possessed by the registrant under 18 U.S.C. 922(o).