Licensed manufacturers and importers must mark firearms they manufacture or import pursuant to 478.92(a)(1).  However, there are exceptions allowing licensed importers and manufacturers to adopt existing markings previously placed on firearms under specified circumstances.

Pursuant to 478.92(a)(4)(iii)(A), licensed manufacturers may adopt the serial number and other identifying markings previously placed on a firearm by another licensed manufacturer provided the firearm has not been sold, shipped, or otherwise disposed of to a person other than a licensee, and the serial number adopted is not duplicated on any other firearm.

Pursuant to 478.92(a)(4)(iii)(B), licensed manufacturers and licensed importers may adopt the serial number or other identifying markings previously placed on a firearm that otherwise meets the requirements of this section that has been sold, shipped, or otherwise disposed of to a person other than a licensee provided that, within the period and in the manner herein prescribed, the licensee legibly and conspicuously places, or causes to be placed, on the frame or receiver either: Their name (or recognized abbreviation), and city and State (or recognized abbreviation) where they maintain their place of business; or their name (or recognized abbreviation) and abbreviated Federal firearms license number, which is the first three and last five digits, individually (i.e., not as a prefix to the serial number adopted) after the letters ‘‘FFL’’, in the following format: ‘‘FFL12345678’’. The serial number adopted must not duplicate any serial number adopted or placed on any other firearm, except that if a licensed importer receives two or more firearms with the same foreign manufacturer’s serial number, the importer may adopt the serial number by adding letters or numbers to that serial number and may include a hyphen.

Although licensees may adopt markings pursuant to the noted regulations, licensee must ensure ALL marking requirements are met under 478.92(a)(1).  For instance, a licensed manufacturer that assembles newly manufactured receivers acquired from another licensee, must also mark the caliber (if not already marked) and model (if not already marked and the licensee assigns a model) of the completed firearm.