18 USC 44 Sec. 923
§ 923(e)
§ 923(k)
(e) The Secretary may, after notice and opportunity for hearing, revoke any license issued under this section if the holder of such license has willfully violated any provision of this chapter or any rule or regulation prescribed by the Secretary under this chapter or fails to have secure gun storage or safety devices available at any place in which firearms are sold under the license to persons who are not licensees (except that in any case in which a secure gun storage or safety device is temporarily unavailable because of theft, casualty loss, consumer sales, backorders from a manufacturer, or any other similar reason beyond the control of the licensee, the dealer shall not be considered to be in violation of the requirement to make available such a device). The Secretary may, after notice and opportunity for hearing, revoke the license of a dealer who willfully transfers armor piercing ammunition. The Secretary's action under this subsection may be reviewed only as provided in subsection (f) of this section.
(k) Licensed importers and licensed manufacturers shall mark all armor piercing projectiles and packages containing such projectiles for distribution in the manner prescribed by the Secretary by regulation. The Secretary shall furnish information to each dealer licensed under this chapter defining which projectiles are considered armor piercing ammunition as defined in section 921(a)(17)(B).