1. Short title This Act may be cited as the Age 21 Act . 2. Prohibition on purchase of certain firearms by individuals under 21 years of age (a) Definitions Section 921(a) of title 18, United States Code, is amended— (1) by inserting after paragraph (29) the following: (30) The term semiautomatic pistol means any repeating pistol that— (A) utilizes a portion of the energy of a firing cartridge to extract the fired cartridge case and chamber the next round; and (B) requires a separate pull of the trigger to fire each cartridge. (31) The term semiautomatic shotgun means any repeating shotgun that— (A) utilizes a portion of the energy of a firing cartridge to extract the fired cartridge case and chamber the next round; and (B) requires a separate pull of the trigger to fire each cartridge.