For many firearm enthusiasts, building firearms at home or in a workshop is an age-old tradition. Generally speaking, fabricating (or assembling) a firearm for personal use is lawful. However, it is crucial that firearm owners understand the somewhat detailed laws in California that govern this practice.

Our topic today is “ghost guns” — are they legal in California?

What is a “Ghost Gun?”

First, a “ghost gun” typically refers to a homemade firearm that does not contain serial numbers. These types of firearms are usually built using gun kits and can easily become untraceable due to the lack of identifying markings.

Dealing with the Department of Justice

Unlike other states, California requires that any person, prior to manufacturing or assembling a firearm, apply to the California Department of Justice (“DOJ”) for a unique serial number or other mark of identification. (Cal. Penal Code § 29180).

To be approved by the DOJ, the applicant must successfully complete the following:

  1. A firearms eligibility check for each transaction;
  2. Present proof of age and identity;
  3. Provide a description of the firearm that he or she owns or intends to manufacture or assemble; and
  4. Have a valid firearm safety certificate or handgun safety certificate. (Cal. Penal Code § 29182).

If approved by the DOJ, the person must then, within 10 days of manufacturing or assembling the firearm, engrave or permanently affix to the firearm the unique serial number or other mark of identification in a manner that meets or exceeds the requirements imposed on licensed firearm dealers under federal law. That generally means the serial number is engraved or cast on the receiver or frame of the firearm. (18 U.S.C. § 923(i)). Keep in mind, there are additional requirements for manufacturing firearms built out of polymer plastic (i.e., 3D printed firearms). Finally, after the serial number is properly affixed to the firearm, the person must immediately notify the DOJ of that fact and provide sufficient information to identify the owner of the firearm, the unique serial number or mark of identification, and the firearm itself.

Individuals who owned a ghost gun prior to the commencement of this law on July 1, 2018, must also go through the same process of applying for a serial number through the DOJ, affix the identifying information within 10 days of receipt, and provide notice and all identifying information to the DOJ immediately after affixing the information to the firearm.

Additional Issues

In California, the sale or transfer of ownership of any firearm privately manufactured or assembled, regardless of whether a DOJ approved serial number has been affixed to the firearm, is absolutely prohibited. Additionally, manufacturing or assembling prohibited assault weapons, machine guns, .50 BMG rifles, or destructive devices is unlawful.

Finally, any new resident to the State of California who previously manufactured or assembled a firearm without a serial number must apply for a serial number or other mark of identification within 60 days of arrival for any firearm the resident wishes to possess in the state.

New Hoops to Jump Through

Individuals interested in building their own firearms will soon be required to jump through additional legal hoops to be permitted to purchase firearm parts. In 2019, California Governor Gavin Newsom signed into law AB-879 which will require as of July 1, 2025, approval by the DOJ for the purchase or transfer of firearm precursor parts through a vendor.

The vendor will also be required to submit records of sales and transfers of firearm precursor parts to the DOJ in return. Sale or transfer of firearm precursor parts to prohibited persons or to persons under 21 years of age will be outright banned. This new law appears to be all-encompassing, as the definition of “firearm precursor part” includes nearly all parts typically used to build a firearm beyond cosmetic accessories.

Federal Regulations

Federal law, on the other hand, generally governs all firearms, but doesn’t otherwise specifically regulate or prohibit ghost guns. However, The Undetectable Firearms Act, now codified in 18 U.S.C. § 922(p)(1)(A), does make it unlawful for any person to manufacture, import, sell, ship, deliver, possess, transfer, or receive any firearm that, after removal of grips, stocks, and magazines, is not detectable through walk-through metal detectors.

Additional federal legislation dealing with and providing further regulation on the possession and manufacturing of ghost guns is already in the legislative process through the introduction of H.R. 1266 – Ghost Guns Are Guns Act, and H.R. 3553 – Untraceable Firearms Act of 2019. These bills, if passed, would generally make ghost guns and the sale of metal milling machines to create ghost guns unlawful.

The Current Status

So, what does this all mean? In California, the possession of a ghost gun currently is unlawful. A person may build or assemble a firearm that is otherwise legal to possess but, in doing so, the person manufacturing the gun must comply with all requirements discussed above, including receipt of approval from the DOJ after submission of all required documents.

For any questions regarding ghost guns in the State of California, contact U.S. LawShield and ask to speak to your Independent Program Attorney.


The preceding should not be construed as legal advice nor the creation of an attorney-client relationship. This is not an endorsement or solicitation for any service. Your situation may be different, so please contact your attorney regarding your specific circumstances. Because the laws, judges, juries, and prosecutors vary from location to location, similar or even identical facts and circumstances to those described in this presentation may result in significantly different legal outcomes. This presentation is by no means a guarantee or promise of any particular legal outcome, positive, negative, or otherwise.