Title 18 USC, Sec. 921 (a)(1)(16) "The term 'antique firearm' means -
(A) any firearm (including any firearm with a matchlock, flintlock, percussion cap, or similar type of ignition system) manufactured in or before 1898; or
(B) any replica of any firearm describe in sub-paragraph (A) if such replica -
(i) is not designed or redesigned for using rim-fire or conventional center-fire fixed ammunition, or
(ii) uses rim-fire or conventional center-fire fixed ammunition which is no longer manufactured in the United States and which is not readily available in the ordinary channels of commercial trade; or
(C) any muzzle loading rifle, muzzle loading shotgun, or muzzle loading pistol, which is designed to use black powder, or a black powder substitute, and which cannot use fixed ammunition. For purposes of this sub-paragraph, the term 'antique firearm' shall not include any weapon which incorporates a firearm frame or receiver, any firearm which is converted into a muzzle loading weapon, or any muzzle loading weapon which can be readily converted to fire fixed ammunition by replacing the barrel, bolt, breech-block, or any combination thereof.