Internal Revenue Code (Title 26 U.S.C.)
26 U.S.C. § 5842 (2024) — Identification of firearms
Identification of firearms other than destructive devices
Each manufacturer and importer and anyone making a firearm shall identify each firearm, other than a destructive device, manufactured, imported, or made by a serial number which may not be readily removed, obliterated, or altered, the name of the manufacturer, importer, or maker, and such other identification as the Secretary may by regulations prescribe.
Firearms without serial number
Any person who possesses a firearm, other than a destructive device, which does not bear the serial number and other information required by subsection (a) of this section shall identify the firearm with a serial number assigned by the Secretary and any other information the Secretary may by regulations prescribe.
Identification of destructive device
Any firearm classified as a destructive device shall be identified in such manner as the Secretary may by regulations prescribe.
Source: official text