80% Lower California Serialization Requirements

Posted by 80-Lower on Jul 30th 2019

Can you still build an AR-15 in California using an 80% lower receiver? Yes, you can! California's legislators are always trying to find ways to make owning a black rifle more difficult for gun owners, so we're going to make it easier (again). This guide will explain the state law, California's AB 857, and what it means for your AR-15 and receiver blank. We'll also explain how to legally serialize your 80% lower!

DISCLAIMER: We're not lawyers, and California's gun laws are complex. Nothing in this guide can be construed as legal counsel or legal advice. If you're unsure about any gun laws in your state, consult with an attorney.

Want it straight from the horse's mouth? Here's California DOJ's document detailing the serial number application process.

What Federal Law Says

Federal law says you can legally build a firearm at home, no paperwork or license required, no serial number required. The Gun Control Act of 1968 (GCA) contains the law describing homemade firearms and their legality. The Bureau of Alcohol, Tobacco, Firearms, and Explosives (BATFE) explains the law and enforces it:

"No, a license is not required to make a firearm solely for personal use. However, a license is required to manufacture firearms for sale or distribution. The law prohibits a person from assembling a non–sporting semiautomatic rifle or shotgun from 10 or more imported parts, as well as firearms that cannot be detected by metal detectors or x–ray machines. In addition, the making of an NFA firearm requires a tax payment and advance approval by ATF."

[18 U.S.C. 922(o), (p) and (r); 26 U.S.C. 5822; 27 CFR 478.39, 479.62 and 479.105]

As of August, 2019, California has not successfully restricted its residents from exercising their Second Amendment rights under this federal law. The Golden State's politicians do not, however, like this law. They're incredibly anti-gun, so they introduced a bill that partially conflicts with the ATF's interpretation of this law: Bill AB 857.

California AB 857 Explained

California's AB 857 was passed and went into effect July 1, 2018. The bill requires all firearms bought, sold, or built in California to have a unique serial number applied to the weapon by January 1, 2019. That includes store-bought guns and your homemade firearm, be it an AR-15 or some other rifle.

AB 857 applies to you if:

  1. You currently own a self-made firearm with no serial number in California as of July 1, 2018, or
  2. You intend to build a self-made firearm in California from a receiver blank or raw materials.

AB 857 Serialization Requirements

If AB 857 applies to you, you'll have to follow California's new unique serialization requirements. That means submitting a "unique serial number application" to California's Department of Justice and getting your serial number issued to you (for a fee). You must then have your serial number applied to your 80% lower, receiver blank, or frame blank before it is legally classified as a firearm.

In fact, there are two applications you must file: A Personal Firearms Eligibility Check application, followed by the Unique Serial Number Application.

How to Request a Serial Number in California

Step 1: Download and submit the PFEC application

The Personal Firearm Eligibility Check (PFEC, labeled "Form BOF 116") Application needs to be downloaded, filled out in black or blue ink, notarized, and submitted to the California DOJ. The PFEC is just an enhanced, state-level background check. It determines that you're eligible to own a firearm in the state of California. You know, since apparently the ATF's own federal background check isn't good enough.

Things to submit with the PFEC

  1. *Right thumbprint impression of fingerprint-identification quality.
  2. Copy of your California driver's license or identification card.
  3. A $20 check or money order payable to "CALIFORNIA DEPARTMENT OF JUSTICE".
  4. Notarization of the PFEC Application by a California public notary.

*You can roll your own thumbprint with a black-ink fingerprint pad, but your public notary can also handle this for you.

Mail your completed PFEC to:


If you have questions about filing your PFEC application, contact the CA DOJ at 916-227-7527 or firearms.bureau@doj.ca.gov. The Department is incredibly unwilling to talk to California residents over the phone. You may need to play around and select certain options when calling to get a live representative on the phone.

Once your PFEC has been submitted, it will take approximately 30 days for your application to be reviewed and approved or rejected. The DOJ says it is recommended you wait for your PFEC application to be approved before submitting your Unique Serial Number Application.

Step 2: Register on California CFARS System

California has at least made some attempt to modernize this bureaucratic serialization process. To submit your Unique Serial Number Application, you'll need to first register on the California Firearms Application Reporting System (CFARS): https://cfars.doj.ca.gov/login.do

Once registered, you can fill out your Unique Serial Number Application (USNA).

Step 3: Fill out and submit the USNA application

The USNA can be completed through the CFARS system. You can also choose to download a written USNA application, to be completed and submitted via email or regular mail.

The written application has some confusing legalese on page 1 regarding California's Assault Weapon Registration in 2017. You can ignore this information since you're simply building a Firearm Manufactured By Unlicensed Subject (FMBUS), not an assault weapon. Page 2 of the application (pictured above) is where you need to begin filling out your personal information.

Submitting your USNA

If completing your USNA request digitally, you can simply submit your application and process your $15 payment for the application via CFARS with a credit or debit card. If you process digitally, you'll receive a decision about your application through email.

If you opt out of using CFARS, we recommend  against submitting the application via email. We recommend mailing your application in with the required payment of $15 via check or money order to:


If you have questions about completing or submitting the USNA application, email the CA DOJ at dojserialnumber@doj.ca.gov.

Step 4: Receive your serial number and engrave it (quickly)

The California DOJ says it takes at least 15 calendar days to process your USNA application. If approved, you'll receive your unique serial number in a determination letter. You then have 10 days to get your serial number engraved on your 80% lower or receiver blank.

Since your 80% lower or receiver blank isn't considered a firearm yet, you can have any machine shop or metallurgist complete your engraving. Your engraving must adhere to the following requirements:

  • Minimum engraved depth of 0.003"
  • Minimum text size no smaller than 1/16"

The engraving must include your serial number and the following information from your USNA application:

  • Model of the firearm
  • City and state of manufacture
  • Caliber or gauge of the firearm
  • Manufacturer's first and last name

Submitting proof of your engraving

Failing to meet the 10-day deadline means your serial number becomes invalid, and you'll need to start the whole application process over. The CA DOJ considers the day they send the email with your application's approval as "day one". You simply need to take photos of the engraved serial number on your new receiver blank and upload them to CFARS as proof.

Step 5: Finish building your black rifle!

With your 80% lower or blank engraved with your California-issued serial number, you're finally in the clear to cut and drill your lower! Doing so turns it into a stripped lower receiver, a firearm that you can finish building with a lower parts kit, upper, buffer assembly, and all your favorite accessories.


That was a lot of information to digest. Want a quick summary?

  • You can build an 80% lower in California, if you apply for a unique serial number first.
  • You need to receive your serial number before you cut and drill your lower receiver.
  • To apply, first submit a Personal Firearm Eligiblity Check (PFEC) application.
  • Next, register on CFARS and submit a Unique Serial Number Application (USNA).
  • You can download the USNA and submit it manually via email or mail, too.
  • Submit the USNA with a $15 fee (paid digitally or by check/money order).
  • Receive your unique serial number, get it engraved, and finish your build.

DISCLAIMER: If you are new to the world of DIY gun building, you likely have a lot of questions and rightfully so. It’s an area that has a lot of questions that, without the correct answers, could have some serious implications. At 80-lower.com, we are by no means providing this content on our website to serve as legal advice or legal counsel. We encourage each and every builder to perform their own research around their respective State laws as well as educating themselves on the Federal laws. When performing your own research, please be sure that you are getting your information from a reliable source.