authority. 106. Definitions In this title: (1) Ammunition The term ammunition has the meaning given such term in section 921(a)(17)(A) of title 18, United States Code. (2) Gun The term gun means firearm as defined in section 921(a)(3) of title 18, United States Code. (3) Gun buyback program The term gun buyback program means a program under which a State, a unit of local government, or a gun dealer, using smart prepaid cards as described in section 105(b)(2), purchases back from individuals wishing to dispose of them, a gun identified by the Director under section 104(b). (4) Gun dealer The term gun dealer means a dealer of firearms licensed under section 923 of title 18, United States Code. (5) Smart prepaid card The term smart prepaid card means a card issued by the Director that— (A) is redeemable at multiple, unaffiliated merchants or service providers