Replica antique muzzle-loading firearms that use black powder and do not fire fixed ammunition are generally exempt from ATF Form 6 import permit requirements and are not classified as 'firearms' under the Gun Control Act. However, they still classify under HTS 9303100000, and importers should confirm the specific article's regulatory status with ATF before importation.

Both inline and traditional muzzle-loading designs load from the muzzle and classify under 9303100000 regardless of ignition system (flintlock, percussion cap, or inline primer). The HTS does not subdivide by ignition mechanism. The regulatory distinction that matters most is whether the firearm uses fixed ammunition, which affects ATF admissibility rather than tariff classification.