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LAWS GOVERNING Licensed manufacturers of ghost gun kits and components

California law requires federally licensed firearm manufacturers to obtain a state license and comply with specified public safety requirements if they manufacture at least 50 firearms in any calendar year in the state.1 For the purposes of this and other laws regulating licensed firearm manufacturers, California law states that the term “firearm” includes the “unfinished frame or receiver of a weapon that can be readily converted to the functional condition of a finished frame or receiver.”2 As a result, federally licensed manufacturers are generally required to obtain a state license, and comply, among other things, with requirements related to site security, employee background checks, and serialization of all unfinished frames or receivers prior to their sale, if they manufacture 50 or more completed firearms or unfinished frames or receivers in California in any calendar year.

Laws Governing Self-Assembled Firearms

In 2016, California enacted a law placing new requirements on anyone who manufactures or assembles a firearm or otherwise possesses an unserialized firearm but does not have a valid firearm manufacturer’s license. This law became effective in 2018, and requires that:

  • Prior to assembling or manufacturing a firearm from a ghost gun kit or components, a person must apply to the California Department of Justice (“DOJ”) for a unique serial number or mark of identification unique to that firearm.3 State law directs DOJ to issue serial numbers to applicants who meet all of the following requirements: (1) have a firearm safety certificate, (2) have completed a firearms eligibility background check verifying that they are eligible to possess firearms under both state and federal law, (3) presented proof of age and identity showing they are at least 21 years of age, and (4) provided a description of the firearm they intend to manufacture or assemble.4
  • After receiving that serial number from DOJ, the person must engrave or permanently affix the unique serial number to their firearm within 10 days of manufacturing or assembling the firearm.5
  • The individual must provide information about the newly serialized firearm, including the identity of the owner of the firearm, to DOJ.6 Firearms manufactured or assembled pursuant to these provisions are for personal use only and generally cannot be sold or transferred.7
  • Anyone in possession of an unserialized firearm must apply to the DOJ for a serial number and must serialize the firearm, or must otherwise relinquish the unserialized firearm to law enforcement.8
  • The law also expressly prohibits individuals or companies from knowingly allowing, facilitating, aiding, or abetting the manufacture or assembly of a firearm by individuals who are prohibited from possessing a firearm under state law.9
  • In addition, California law does not authorize people to assemble prohibited weapons such as assault weapons, machine guns, or handguns that have not passed testing and certification requirements under California’s Unsafe Handgun Act consumer safety law.10
    • Note: it appears that no retail sellers of ghost gun kits have complied with California’s Unsafe Handgun Act by submitting their handgun designs for testing and certification by California’s Department of Justice. The Unsafe Handgun Act requires that new handgun models incorporate specified consumer and public safety features and be tested by independent laboratories to ensure they can pass basic safety and reliability standards. It is a crime under California law to manufacture or cause the manufacture of handgun models that have not been tested and certified under this consumer protection law.11 See our Design Safety Standards in California page for a comprehensive discussion of these requirements.

Laws Governing the sale of ghost gun kits and components

Compared to some other states, California law has provided dangerously weaker protections regarding the sale of ghost gun components, contributing to a dangerous, exploding market for these products within the state. This is a particularly attractive source of weaponry for people who know they would not pass the background check required to acquire completed firearms in California or who wish to conceal their involvement in gun trafficking or other illegal activities.

In 2019, California acted to address this growing threat to public safety by enacting legislation that will, when implemented, begin to meaningfully regulate the sale of unfinished firearm frames and receivers.12 (This legislation was originally set to go into full effect in July 2025, but California passed a law in 2020 to expedite implementation of most of these new requirements to July 1, 2022).13

Once in effect, this law will treat the sale of unfinished frames and receivers (defined as “firearm precursor parts”) in a manner similar to the sale of ammunition under California law by requiring:

  • Sellers of firearm precursor parts to obtain a state business license (called a “firearm precursor part vendor license”) in order to sell more than one precursor part in any 30-day period;14
  • The sale of precursor parts by any party to be conducted in-person through licensed precursor part vendors, pursuant to a background check and sale record;15
  • Licensed precursor part vendors to comply with other public safety laws similar to those governing firearm dealers and ammunition vendors under California law, including ensuring employees who handle firearm precursor parts regularly pass background checks and restrictions on trafficking of firearm precursor parts or delivery of such products to minors under 21 or to other people who are ineligible to receive them.16

    Note that federal law may provide stronger protections and requirements on sellers of ghost gun kits and components by defining as a firearm any weapon which may be readily converted to fire ammunition, or the frame or receiver of any such weapon.17


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  1. Cal. Penal Code § 29010.[]
  2. Cal. Penal Code § 16520(g).[]
  3. Cal. Penal Code §§ 29180(b)(1); 29182.[]
  4. Cal. Penal Code §§ 29182(b).[]
  5. Cal. Penal Code §§ 29180(b)(1); 29180(b)(2)(A). If the firearm is made from plastic, the serial number must be engraved or affixed on a piece of metal large enough to be detected by metal detectors and embedded within the plastic. Cal. Penal Code § 29180(b)(2)(B).[]
  6. Cal. Penal Code. § 29180(b)(3).[]
  7. Cal. Penal Code § 29180(d).[]
  8. Cal. Penal Code § 29180(c).[]
  9. Cal. Penal Code § 29180(f).[]
  10. Cal. Penal Code § 29182(e).[]
  11. Cal. Penal Code § 32000(a).[]
  12. See 2019 CA AB 879.[]
  13. 2019 CA SB 118, Sec. 21 – 37.[]
  14. Cal. Penal Code §§ 30442; 30485; 16532[]
  15. Cal. Penal Code §§ 30412; 30414; 30452[]
  16. See Cal. Penal Code §§ 30400 – 30495.[]
  17. See 18 U.S.C § 921(a)(3).[]