11th Jan 2021

80% Lowers and California as of 2020

* This blog post is intended to inform but should not be relied upon as a final say in the ever changing nature of California's draconian restrictions on firearm related items. Please use discretion and do your own research when completing any 80% receiver as the legalities vary wildly by state. This post borrows liberally from other 80% lower vendors websites as we are busy designing new parts instead of attempting to make sense of the stupid misguided and often contradictory nature of liberal politics. I am truly sorry for the nature of your geographic situation. 

**** If you are a California resident we can and will engrave your 80% lower serial number here at Tennessee Arms for a nominal fee. Some of these steps need to be completed prior to us shipping the receiver to you so we know what to engrave. You WILL NOT find a more cost effective option. ***

AB 857 and What it Means for 80% Lowers in California

California's AB 857 legislation dictates that:

  • All finished firearms possessed by individuals in the state must have a serial number engraved.
  • Any weapons made prior to July 1, 2018 require a serial number to be engraved on the weapon, though the serial number nor the weapon itself needs to be reported to the California Department of Justice.
  • Any 80% lower finished after July 1, 2018 needs to have a unique serial number engraved on the weapon which is assigned to it by the California Department of Justice through an application process.
  • If you finished an 80% lower before July 1, 2018, there is no reasonable way for the California DOJ to prove that you built your 80% lower after the deadline. Take that with a grain of salt and let the implication sink in.
  • You can still buy an 80% lower without any paperwork, but you can't legally fabricate it into a firearm until you have a serial number approved and assigned by the state.

The California PFEC Background Check

Download the PFEC Application Here.

The PFEC must be completed as a paper application and mailed to the California DOJ with a $20 check or money order. The application must be notarized and you must apply a thumbprint fingerprint to the application itself. Instructions are provided on the application for where and how to mail it. Once your application has been submitted, you must wait for the PFEC to be approved by the state before submitting an application for a unique serial number for your lower receiver.

The California Unique Serial Number Application

Once your PFEC is approved, you can register on the California Firearms Application Reporting System. This is the website where you'll make an account and apply for a unique serial number for your 80% lower receiver.

Once you've registered on CFARS, you'll be able to log in and see an application for a unique serial number on the website's dashboard. Simply fill out the application, submit a $15 payment via your debit or credit card, and then wait patiently for your application to be processed.


The only required fields you should fill out under "Firearm Information" are:

  • Firearm Type
  • Firearm Color
  • Date of Manufacture
  • Material

Leave the optional fields blank and do not upload any files to the application. Once you've submitted your serial number application, it'll take approximately 15 calendar days for it to be approved or rejected. Once your application is approved, you'll have 10 calendar days to engrave your assigned serial number on your receiver. You must also upload a picture of the finished engraving onto the CFARS website, or your application and serial number will be retroactively rejected.

The Serial Number Marking ( this is the part we can do for you if you would like

The serial and markings on your lower receiver have to follow some strict guidelines in order to be a legal firearm in California, or any state:

  • Markings must be at least .003" deep.
  • Markings must include the serial number.
  • Marking font size cannot be smaller than 1/16".
  • Markings must use "A-to-Z" letters and "0-to-9" numbers only.
  • Markings must include the caliber.
  • Markings must include the maker's name (that's you).
  • Markings must include the city and state of manufacture (where you live).
  • Markings must include the weapon model (if you entered one on the CFARS application).

Serializing your lower can be a messy process if you try doing it at home without the right tools. There are aluminum engraving tools available, but these are expensive and usually not worth the one-time cost if you're an at-home builder. We recommend taking your unfinished lower to a CNC shop or metallurgist so they can serialize it before you begin machining yourself. Since an un-fabricated 80% lower isn't considered a firearm, any engraving service can complete this for you. It doesn't have to be a gunsmith or FFL who engraves your receiver.

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