N.J. Admin. Code § 13:54-4.15
Each registered manufacturer of firearms shall legibly identify each firearm manufactured by engraving, casting, stamping, or otherwise conspicuously placing or causing to be engraved, cast, stamped or placed on the frame, receiver or barrel thereof in a manner not susceptible to being readily obliterated, altered, or removed, an individual serial number not duplicating any serial number placed on any other firearm manufactured and by engraving, casting, stamping, or otherwise conspicuously placing or causing to be engraved, cast, stamped or placed on the frame, receiver, or barrel thereof in a manner not susceptible to being readily obliterated, altered or removed, the model, if such designation has been made; the caliber or gauge; the name of the manufacturer and also, the city wherein the registered manufacturer maintains his place of business. A firearm frame, receiver or barrel which is not a component part of a complete firearm at the time it is sold, shipped or otherwise disposed of by a registered manufacturer shall be identified as required by this subchapter.
N.J. Admin. Code § 13:54-4.15