Pen. Code, § 29180

(a) For purposes of this chapter, “manufacturing” or “assembling” a firearm means to fabricate or construct a firearm, including through additive, subtractive, or other processes, or to fit together the component parts of a firearm to construct a firearm.

(b) Before manufacturing or assembling a firearm, a person manufacturing or assembling the firearm shall, for any firearm that does not have a valid state or federal serial number or mark of identification imprinted on the frame or receiver, do all of the following:

(1) (A) Apply to the Department of Justice for a unique serial number or other mark of identification pursuant to Section 29182.

(B) Each application shall contain a description of the firearm that the applicant intends to assemble, the applicant’s full name, address, date of birth, and any other information that the department may deem appropriate.

(2) (A) Within 10 days of manufacturing or assembling a firearm in accordance with paragraph (1), the unique serial number or other mark of identification provided by the department shall be engraved or permanently affixed to the firearm in a manner that meets or exceeds the requirements imposed on licensed importers and licensed manufacturers of firearms pursuant to subsection (i) of Section 923 of Title 18 of the United States Code and regulations issued pursuant thereto.

(B) If the firearm is manufactured or assembled from polymer plastic, 3.7 ounces of material type 17-4 PH stainless steel shall be embedded within the plastic upon fabrication or construction with the unique serial number engraved or otherwise permanently affixed in a manner that meets or exceeds the requirements imposed on licensed importers and licensed manufacturers of firearms pursuant to subsection (i) of Section 923 of Title 18 of the United States Code and regulations issued pursuant thereto.

(3) After the serial number provided by the department is engraved or otherwise permanently affixed to the firearm, the person shall notify the department of that fact in a manner and within a time period specified by the department, and with sufficient information to identify the owner of the firearm, the unique serial number or mark of identification provided by the department, and the firearm in a manner prescribed by the department.

(c) Any person who owns a firearm or firearm precursor part that does not bear a valid state or federal serial number or mark of identification shall be deemed to be in compliance with subdivision (b) of Section 23920 if they comply with all of the following:

(1) (A) By no later than January 1, 2024, or if a new resident of the state, within 60 days after arriving in the state with a firearm that does not have a valid state or federal serial number or mark of identification, apply to the Department of Justice for a unique serial number or other mark of identification pursuant to Section 29182.

(B) An application to the department for a serial number or mark of identification for a firearm precursor part shall include, in a manner prescribed by the department, information identifying the applicant and a description of the firearm that the applicant intends to manufacture or assemble with the firearm precursor part, and any other information that the department may deem appropriate.

(2) Within 10 days of receiving a unique serial number or other mark of identification from the department, engrave or permanently affix that serial number or mark of identification to the firearm in accordance with regulations prescribed by the department pursuant to Section 29182 and in a manner that meets or exceeds the requirements imposed on licensed importers and licensed manufacturers of firearms pursuant to subsection (i) of Section 923 of Title 18 of the United States Code and regulations issued pursuant thereto. If the firearm is manufactured or assembled from polymer plastic, 3.7 ounces of material type 17-4 PH stainless steel shall be embedded within the plastic upon fabrication or construction.

(3) After the serial number provided by the department is engraved or otherwise permanently affixed to the firearm, notify the department of that fact in a manner and within a time period specified by the department and with sufficient information to identify the owner of the firearm, the unique serial number or mark of identification provided by the department, and the firearm in a manner prescribed by the department.

(d) (1) Except by operation of law, a person, corporation, or firm that is not a federally licensed firearms manufacturer shall not sell or transfer ownership of a firearm, as defined in subdivision (g) of Section 16520, if any of the following are true:

(A) That person, corporation, or firm manufactured or assembled the firearm.

(B) That person, corporation, or firm knowingly caused the firearm to be manufactured or assembled by a person, corporation, or firm that is not a federally licensed firearms manufacturer.

(C) That person, corporation, or firm is aware that the firearm was manufactured or assembled by a person, corporation, or firm that is not a federally licensed firearms manufacturer.

(2) Paragraph (1) does not apply to the transfer, surrender, or sale of a firearm to a law enforcement agency.

(3) Any firearms confiscated by law enforcement that do not bear an engraved serial number or other mark of identification pursuant to subdivision (b) or (c), or a firearm surrendered, transferred, or sold to a law enforcement agency pursuant to paragraph (2) shall be destroyed as provided in Section 18005.

(4) Sections 26500 and 27545, and subdivision (a) of Section 31615, do not apply to the transfer, sale, or surrender of firearms to a law enforcement agency pursuant to paragraph (2).

(e) A person, corporation, or firm shall not knowingly allow, facilitate, aid, or abet the manufacture or assembling of a firearm by a person who is within any of the classes identified by Chapter 2 (commencing with Section 29800) or Chapter 3 (commencing with Section 29900) of Division 9 of this code, or Section 8100 or 8103 of the Welfare and Institutions Code.

(f) A person, corporation, or firm shall not knowingly manufacture or assemble, or knowingly cause, allow, facilitate, aid, or abet the manufacture or assembling of, a firearm that is not imprinted with a valid state or federal serial number or mark of identification.

(g) If the firearm is a handgun, a violation of this section is punishable by imprisonment in a county jail not to exceed one year, or by a fine not to exceed one thousand dollars ($1,000), or by both that fine and imprisonment. For all other firearms, a violation of this section is punishable by imprisonment in a county jail not to exceed six months, or by a fine not to exceed one thousand dollars ($1,000), or by both that fine and imprisonment. Each firearm found to be in violation of this section constitutes a distinct and separate offense. This section does not preclude prosecution under any other law providing for a greater penalty.