1. Short title This Act may be cited as the Gas-Operated Semi-Automatic Firearms Exclusion Act or the GOSAFE Act . 2. Restrictions (a) Definitions Section 921(a) of title 18, United States Code, is amended by adding at the end the following: (38) The term semi-automatic firearm means any firearm that— (A) upon initiating the firing sequence, fires the first chambered cartridge and uses a portion of the energy of the firing cartridge to— (i) extract the expended cartridge case; (ii) chamber the next round; and (iii) prepare the firing mechanism to fire again; (B) requires a separate pull, release, push, or initiation of the trigger to fire each cartridge; and (C) is not a machinegun. (39) The term cycle the action , with respect to a firearm, means to extract the fired cartridge case, chamber the next cartridge, and prepare the firing mechanism to fire again. (40) The term gas-operated , with respect to a semi-automatic firearm, means any firearm that harnesses or traps a portion of the high-pressure gas from a fired cartridge to cycle the action using— (A) a long stroke piston, where gas is vented from the barrel to a piston that is mechanically fixed to the bolt group and moves to cycle the action; (B) a short stroke piston, where gas is vented from the barrel to a piston that moves separately from the bolt group so that the energy is imparted through a gas piston to cycle the action; (C) a system that traps and vents gas from either the barrel or the chamber to directly strike or impinge the bolt, bolt carrier, or slide assembly, to unlock and cycle the action; (D) a hybrid system that combines elements of a system described in subparagraph (C) with a system described in subparagraph (A) or (B) to capture gas vented from the barrel to cycle the action; (E) a blowback-operated system that directly utilizes the expanding gases of the ignited propellant powder acting on the cartridge case to drive the breechblock or breech bolt rearward