[FAQ] 80% Lowers in California

Living in California as a freedom-loving gun owner has always been a challenge

Sometimes it almost seems like the politicians in Sacramento just sit around thinking of ways to chip away at more of our 2nd Amendment rights. 

But hey, at least the weather is nice, right?

BLM Target Shooting
Desert Target Shooting

But as the saying goes, “necessity is the mother of invention.” 

With all of the laws surrounding magazine size limits, “assault weapon” bans, and ammo regulation, firearms enthusiasts in the state have come up with a variety of ways to overcome these obstacles put in our way. 

The new laws recently passed regarding unfinished receivers is no different.

CA Featureless Rifle Grips
CA Featureless Rifles

While 80% lowers have been around for a while, there has been a recent increase in interest, as the technology to complete these unfinished lowers becomes more affordable to gun owners. 

Of course, we can’t have anything fun in California without some helpful input from the state legislature, so when it comes to 80% lowers, there are rules that every firearm owner in the state needs to be aware of. 

Disclaimer:  While the information provided here is legal in nature, it is not to be construed as legal advice, and is for educational and entertainment purposes only.  

Last Updated: November 10, 2019

Table of Contents


Unfinished Business

Before we get into all the rules and regulations for unfinished lowers in California, it’s important to make sure we’re all on the same page.

As this really gets into the realm of manufacturing firearms, and that is one area where you absolutely want to make sure you are following the letter of the law.

Red Flag Laws (4)
If only “Shall Not Be Infringed” were applied the same way, Legalinsurrection.com

First things first, an “80% lower” is not a legal term used by the ATF or anyone else. 

In fact, an “80% lower” is also referred to as an “80% receiver,” “80% complete,” “80% lower receiver,” or “unfinished receiver.” 

Of these terms, only the phrase “unfinished receiver” is used in California gun laws. As the names imply, the terms simply refer to an unfinished lower receiver or frame, of either a rifle or handgun.  

80% AR-15 Lowers, All Sides
“Unfinished Receivers”

What Does This Matter?

It may seem like a silly name or even concept to have something unfinished, but it is actually a very important distinction when it comes to the legal definition of a “firearm.”  

Under the Gun Control Act of 1968, which regulates firearms and firearms owners, a “firearm” means:

  1. Any weapon which will or is designed to or may readily be converted to expel a projectile by the action of an explosive; 
  2. The frame or receiver of any such weapon; 
  3. Any firearm muffler or firearm silencer; or
  4. Any destructive device.

What we’re mainly concerned with when it comes to 80% lowers, is that second definition. 

80% Arms Lowers
80% Arms Lowers, see how the trigger pack area is filled in and there are no pinholes drilled in the side. These are “Unfinished” AR-15 lowers.

Even though we typically think of an actual gun as a firearm, the law considers just the frame or receiver of a gun to be a firearm as well.  

A firearm frame or receiver is further defined as “that part of a firearm which provides housing for the hammer, bolt or breechblock, and firing mechanism, and which is usually threaded at its forward portion to receive the barrel.”  

This is the reason that when you go buy a lower for your new rifle build, you actually have to go through the same purchase process as you would a completed rifle, because, under the eyes of the law, both a stripped lower and a fully assembled rifle are “firearms.”  

Couple AR Lowers
4 stripped AR-15 lowers, this is the regulated part of the AR-15.

An 80% lower, however, is technically not a frame or receiver as it is legally defined, since it is missing the housing for the hammer, bolt, and firing mechanism, and so cannot be considered a firearm. 

80% Arms Receivers
80% Arms Receivers

Because of that, all of the rules and regulations that go along with the purchase of a firearm go out the window.

You’re basically just buying a piece of metal (usually aluminum) or some type of polymer plastic, and it’s up to you cut out and drill the spacing needed for all that housing.  

What’s The Point?

Now that we have the legal stuff out of the way, what’s the craze over 80% lowers? 

Well, aside from the fact you can buy an unfinished receiver online and have it shipped to your house, your 80% lower can be completed on your own time, however you want. 

Additionally, since it’s just a piece of metal or plastic, there’s no serial number, no registration, or any of the other fun things Big Brother wants you to do when you buy a gun.

Now What?

This is a good time to mention that even though we were focused on the second definition of a firearm under the Gun Control Act of 1968, that first definition comes into play once you actually get the 80% lower in your hands. 

Under the first definition, a firearm is any weapon that may readily be converted to expel a projectile by the action of an explosive.  

In other words, by definition, anything that isn’t a firearm cannot be something that is easily converted into a firearm.  With an 80% lower, you still have, if my math is correct, 20% of the way to go to complete the lower!

Hangover Math Gif
ATF Looking At A Block Of Metal And Deciding If It Is A Firearm Or Not, 2019, Colorized

Anyone who has completed an unfinished receiver will agree that it definitely is not something that can be “readily converted” into a firearm.

The traditional method of finishing up that last 20% of an unfinished receiver required a drill press and a milling machine, and a couple hours to kill. 

If you want to get fancy, a CNC machine could do a much better job, taking a lot of the human error out of the machining process.  

With recent innovations in the area, however, if you have the money, you can have the same results with just a router, drill, and a lot of patience. 

Easy Jig 2 and Router
Easy Jig 2 and Router

If that sounds right up your alley, definitely check out our review of the Easy Jig 2 for one of the better options on the market today when it comes to rifle lowers.  

Drilling Firing Control Group Hole
Drilling Firing Control Group Hole Using The Easy Jig 2

Early Dismissal

At this point, if you don’t live in California, you’ve got all you need to know about 80% lowers! 

If you’re looking for a guide on the actual process of completing a lower, we’ll have an upcoming article going over the most effective processes we’ve found in finishing up that last 20% of the work.

In the meantime, you can go buy a couple of unfinished receivers and try your hand at finishing them. 

Even if you screw up, they’re pretty cheap, and you’ll have some cool paperweights to give away at Christmas!

But If You Do Live In California…

Sadly, since this is California, we’re not done yet… The rest of us need to stay in class and finish the lecture before we are allowed to go out and play.

Even if you aren’t from California, you’re welcome to read on and see just how much better you have in your fancy 2A-respecting state.  

40+ states reaction when they see anything about the second amendment and California in the same sentence

Some Restrictions May Apply

The idea of an 80% lower is great and all, but is it even legal in California? 

By some miracle, unfinished lowers are actually legal in the state of California.  For now, anyway. But, it is California after all, so you’ll need to jump through some hoops and give up some of your natural-born rights if you want anything more than a paperweight. 

Oh, and by the way, you’ll be legally prohibited from selling or transferring ownership of your completed firearm. But hey, it’s only confiscated when you die, so it’s fine.     

The good news is that you can buy an 80% lower just like your friends who live in free states.  In fact, you can even go buy one right now and have it shipped to your door! Check out more of our favorite 80% lowers.

Best Value
at Brownells

Prices accurate at time of writing

Prices accurate at time of writing

All from the comfort of your toilet seat.  The problems come when you actually want to finish that last 20% of the lower.  

Finishing Touches

In order to finish a lower receiver and make it into a firearm, you’ll need to register your soon-to-be finished lower. 

Part of the registration process involves putting a serial number onto the receiver. And not just any serial number either. 

Serial Number for Ruger Precision Rifle
It will depend on your firearm, but generally, the serial number is easy to find.

You can’t just etch a “6969420” onto your lower with a knife and call it a day.

The serial number on your lower must be one assigned to you by the CA DOJ.

Since the serial number is a required part of making a firearm, in transforming your 80% lower into a useable lower receiver, you’ll need to go through a background check just like you would with a standard firearm, with anyone who is not allowed to own or handle firearms being automatically denied a serial number for their lower.

Just like with the purchase of firearms, you’ll also need to make sure you provide acceptable identification, and have a firearm safety certificate.  

You do have your papers, right?

With the transition to Real ID driver licenses, anyone who has a California driver license that is not a Real ID driver license, will need to provide additional proof of identity, including any of the following:

  1. A valid, unexpired US passport;
  2. A US birth certificate;  
  3. A valid, unexpired foreign passport with valid US immigrant visa;
  4. A Certificate of Naturalization or US citizenship; or
  5. A valid, unexpired Permanent Resident Card.
Real ID on the left, slightly less useful California driver license on the right.

Once you have all of that out of the way, you’ll be ready to actually apply for a serial number using the California Firearms Application Reporting System (CFARS).  

The application process itself is pretty self-explanatory, though you do need to keep in mind that if you are applying for a serial number for an unfinished handgun frame, you need to be 21 or older, just like you would if you were buying a handgun.  

If everything goes smoothly, you should receive your serial number from the CA DOJ, and within 10 days of receiving the serial number, you must have the number engraved on your lower.  

air quotes
“If it goes smoothly”

Aside from having to give up personal information about yourself and being placed on a registry of firearms owners, applying for a serial number you are required to engrave onto your homemade lower isn’t all that bad! 

To be fair, CA DOJ probably already has your information from those other guns you’ve purchased in the past, so there’s that.   

But Wait, There’s More!

Just because you managed to get a serial number doesn’t mean you’re out of the woods quite yet. 

You’ll still need to complete the registration process by sending picture proof of your serial number placed on the finished lower. 

What’s more, the engraving of the serial number itself has specific requirements as well.

The serial number must be engraved, cast, stamped, or somehow permanently placed in a location on the receiver or frame of the firearm that is clearly visible, and must be placed in a way that is not easily obliterated, altered, or removed. 

And as a general reminder, don’t forget that removing, obliterating, or altering a firearm’s serial number is very illegal.

More importantly, the serial number has to be engraved or somehow permanently fixed into the lower with a minimum depth of at least 0.003 inches, with a minimum of 1/16 inch print.

In addition to the serial number, a few other pieces of information are also required to be engraved or permanently fixed to the receiver, including:

  1. The model of the firearm (if it has one); 
  2. The caliber or gauge of the firearm; 
  3. The manufacturer’s first and last name (your name, since you’re the one completing the lower); and
  4. The city and state where the firearm was made.

The good news is that you don’t have to do the engraving yourself, and can take it to anyone who is capable of performing the engraving, even if they are not an FFL and have nothing to do with the firearms industry at all. 

All you need is to make sure you put all of that required information onto your lower after you’ve received the serial number.

If that still sounds like a hassle, there are some vendors who offer engraving services included in the price of the lower, so it will be engraved before it arrives at your front door, and all you’d need to do afterward is make the actual cuts in your 80% lower. 

Of course, you’d still have to go through the registration process with CFARS to get the serial number, but it is one less step to worry about if you want to get out and pew pew ASAP.

Whichever way you decide to go, you’ll need to send pictures of the engraved lower through CFARS for the CA DOJ to make their final decision on approving your 80% lower.  

Look Out Ahead!

Some bad news.  In the time you were reading this article, some new gun control laws were passed. 

Just kidding. They were passed a long time ago.  

Because it’s not enough to just make gun owners register their 80% lowers and literally have their first and last name engraved onto their firearms, the state legislature recently passed a law that will require, starting on July 1, 2024, sales and transfers of any “precursor parts” of firearms to be made through an FFL.  

That means the 80% lowers that you can currently order and ship to your house will require a trip to your FFL instead. 

Even just transferring that unfinished lower to your friend will require the FFL to approve the transfer, just like is required with a firearms transfer.  

A background check requirement on those types of purchases will also kick in a year later on July 1, 2025. 

As part of that background check, FFLs will be required to send records of sales and transfers to the CA DOJ like with actual firearms.  

For now, a “precursor part” only covers unfinished receivers for rifles, and unfinished handgun frames.  There’s still a few years to go, so that definition may change to include a lot more than just that by the time the law goes into effect.  

Just like with firearms and ammo, when the law kicks in on July 1, 2024, since all purchases and transfers of 80% lowers have to be made through an FFL, bringing back any purchases you made from out of state will also be illegal.  


With all of these new laws surrounding 80% lowers and additional ones kicking in within the next few years, California residents still interested in trying their hand at completing an unfinished receiver need to get in on the fun while they still can!  

While the new rules won’t come into effect for a few years, there may be a run on 80% lowers and engraving services as we get closer to the deadline, with possible shortages on items, or even vendors refusing to ship to California to avoid dealing with our gun control laws. 

It doesn’t hurt to have a couple of unfinished receivers ready to go for when you finally decide to turn it into your next shiny new range toy.  

In the meantime, get out there and pew pew (while you still can!)

Still thinking about an 80% project after all these CA hoops? Be sure to check out our Best 80% Receivers & Jigs for our top picks.

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2 Leave a Reply

  • Bryan

    Did this change January 1, 2020?

    1 month ago
  • Ian VanVranken

    I can write a real short guide on 80% receivers in NJ... NOPE!

    5 months ago
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