Ok, so serial number is covered.
You need to add Maker’s name, plus the City & State where the firearm is made. That can be on the receiver or barrel.
The caliber also has to be marked. That’s usually on the barrel. So even if the lower says “multi” you’re covered.
I did have one build where the lower said multi, and I was chopping down a longer barrel and lost the markings, so that on that one I had to engrave caliber as well.
The new CFR that came out in August doesn't allow for barrel marking of makers marks any more. Some interesting stuff here. The barrel as an option for name, city and state is gone. ..
§ 479.102 Identification of firearms.
(a) Identification required. Except as otherwise provided in this section, you, as a
manufacturer,
importer, or maker of a
firearm, must legibly identify the
firearm as follows:
(1) Serial number, name, place of business. By engraving, casting, stamping (impressing), or otherwise conspicuously placing or causing to be engraved, cast, stamped (impressed) or otherwise placed on the
frame or receiver thereof, an individual serial number, in a manner not susceptible of being
readily obliterated, altered, or removed. The serial number must not duplicate any serial number placed by you on any other
firearm. The
frame or receiver must also be marked with either: Your name (or recognized abbreviation), and city and State (or recognized abbreviation) where you as a
manufacturer or
importer maintain your place of business, or in the case of a maker, where you made the
firearm; or if a
manufacturer or
importer, your name (or recognized abbreviation) and the serial number that begins with your abbreviated Federal
firearms license number, which is the first three and last five digits, as a prefix to a unique identification number, followed by a hyphen, e.g., “12345678-[unique identification number]”; and
(2) Model, caliber or gauge, foreign manufacturer, country of manufacture. By engraving, casting, stamping (impressing), or otherwise conspicuously placing or causing to be engraved, cast, stamped (impressed) or placed on the
frame or receiver, or barrel or
pistol slide (if applicable) thereof certain additional information. This information must be placed in a manner not susceptible of being
readily obliterated, altered, or removed. The additional information shall include:
(i) The model, if such designation has been made;
(ii) The caliber or gauge;
(iii) When applicable, the name of the foreign
manufacturer or maker; and
(iv) In the case of an imported
firearm, the name of the country in which it was manufactured. For additional requirements relating to imported firearms, see Customs regulations at
19 CFR part 134.
(3) Multi-piece frame or receiver. In the case of a multi-piece
frame or receiver, the modular subpart that is the outermost housing or structure designed to house, hold, or contain either the primary energized component of a handgun, breech blocking or sealing component of a projectile weapon other than a handgun, or internal sound reduction component of a
firearm muffler or
firearm silencer, as the case may be, shall be the subpart of a multi-piece
frame or receiver identified in accordance with this section. If more than one subpart is similarly designed to house, hold, or contain such primary component (e.g., left and right halves), each of those subparts must be identified with the same serial number and associated licensee information not duplicated on any other
frame or receiver. The identified subpart(s) of a complete (assembled or unassembled) multi-piece
frame or receiver shall not be removed and replaced (see
§ 478.34 of this subchapter,
18 U.S.C. 922(k), and
26 U.S.C. 5861(g) and (h)), unless -
(i) The subpart replacement is not a
firearm under
26 U.S.C. 5845;
(ii) The subpart replacement is identified by the qualified
manufacturer of the original subpart with the same serial number and associated licensee information in the manner prescribed by this section; and
(iii) The original subpart is destroyed under the
manufacturer's control or direct supervision prior to such placement.
(4) Frame or receiver, machine gun conversion part, or silencer part disposed of separately. Each part defined as a
frame or receiver or modular subpart thereof described in
paragraph (a)(3) of this section, machinegun, or
firearm muffler or
firearm silencer that is not a component part of a
complete weapon or
complete muffler or silencer device at the time it is sold, shipped, or otherwise disposed of by you must be identified as required by this section with an individual serial number not duplicated on any other
firearm and all additional identifying information, except that the model designation and caliber or gauge may be omitted if that information is unknown at the time the part is identified.
(5) Size and depth of markings. The engraving, casting, or stamping (impressing) of the serial number and additional information must be to a minimum depth of .003 inch, and the serial number and any associated license number in a print size no smaller than 1/16 inch. The size of the serial and license number is measured as the distance between the latitudinal ends of the character impression bottoms (bases). The depth of all markings required by this section is measured from the flat surface of the metal and not the peaks or ridges.
(6) Period of time to identify firearms. You, as a
manufacturer, shall identify a
complete weapon or
complete muffler or silencer device no later than close of the next business day following the date the entire manufacturing process has ended for the weapon or device, or prior to disposition, whichever is sooner. You must identify each part or modular subpart defined as a
machine gun (frame or receiver, or conversion part) or
muffler or silencer that is not a component part of a
complete weapon or
complete muffler or silencer device at the time it is sold, shipped, or otherwise disposed of no later than close of the next business day following the date the entire manufacturing process has ended for the part, or prior to disposition, whichever is sooner. For purposes of this paragraph,
firearms awaiting materials, parts, or equipment repair to be completed are presumed, absent reliable evidence to the contrary, to be in the manufacturing process.
Importers must identify imported
firearms within the period prescribed in
§ 478.112 of this subchapter.
(7) Meaning of marking terms. For purposes of this section, the term “identify” means placing marks of identification, the terms “legible” and “legibly” mean that the identification markings (including any unique identification number) use exclusively Roman letters (e.g., A, a, B, b, C, c) and Arabic numerals (e.g., 1, 2, 3), or solely Arabic numerals, and may include a hyphen, and the terms “conspicuous” and “conspicuously” mean that the identification markings are capable of being easily seen with the naked eye during normal handling of the
firearm and are unobstructed by other markings when the
complete weapon or device is assembled.
(b) Exceptions -
(1) Alternate means of identification. The
Director may authorize other means of identification to identify
firearms upon receipt of a letter application or prescribed form from you showing that such other identification is reasonable and will not hinder the effective administration of this part.
(2) Destructive devices. In the case of a
destructive device, the
Director may authorize other means of identification to identify that weapon upon receipt of a letter application or prescribed form from you. The application shall show that engraving, casting, or stamping (impressing) such a weapon as required by this section would be dangerous or impracticable and that the alternate means of identification proposed will not hinder the effective administration of this part.
