§ 479.102 How must firearms be identified?
(a) You, as a manufacturer, importer, or maker of a firearm, must legibly identify the firearm as follows:
(1) By engraving, casting, stamping (impressing), or otherwise conspicuously placing or causing to be engraved, cast, stamped (impressed) or
placed on the frame or receiver thereof an individual serial number. The serial number must be placed in a manner not susceptible of being readily obliterated, altered, or removed, and must not duplicate any serial number placed by you on any other firearm. For firearms manufactured,
imported, or made on and after January 30, 2002, the engraving, casting, or stamping (impressing) of the serial number must be to a minimum depth
of .003 inch and in a print size no smaller than 1/16 inch;and
(2) By engraving, casting, stamping (impressing), or otherwise conspicuously placing or causing to be engraved, cast, stamped (impressed), or
placed on the frame, receiver, or barrel thereof certain additional information. This information must be placed in a manner not susceptible of being readily obliterated, altered or removed. For firearms manufactured, imported, or made on and after January 30, 2002, the engraving, casting, or stamping (impressing) of this information must be to a minimum depth of .003 inch. The additional information includes:
(i) The model, if such designation has been made;
(ii) The caliber or gauge;
(iii) Your name (or recognized abbreviation) and also, when applicable, the name of the foreign manufacturer or maker;
(iv) In the case of a domestically made firearm, the city and State (or recognized abbreviation thereof) where you as the manufacturer maintain your place of business, or where you, as the maker, made the firearm; and
(v) In the case of an imported firearm, the name of the country in which it was manufactured and the city and State (or recognized abbreviation thereof) where you as the importer maintain your place of business. For additional requirements relating to imported firearms, see Customs regulations at 19 CFR part 134.