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Are 80% Lowers Legal?

Posted by 80-lower on Oct 1st 2018

Are 80% Lowers Legal?

In the modern political atmosphere, one common question about 80% lowers is whether or not they are legal. This is an understandable question, but we feel that it is necessary to give a clear answer on the current state of the law revolving around 80% lowers.

Keep in mind that laws can change quickly. As we just saw with bump stocks, these types of things can move very fast, especially considering the current state of gun laws and those that oppose gun ownership.

The Basics

Since you’re curious about the legality of 80% lowers, it’s safe to assume that you know what an 80% lower receiver or an 80% frame of a weapon is. But, just to be sure, we will cover the most basic concept first. An 80% lower or 80% frame is essentially a part of a weapon that can be purchased, milled in some fashion, and then created into a firearm.

Right off the bat, you can see why there might be a little skepticism with regards to the legality of these lowers. Essentially, with a few tools and a little mechanical know-how, someone could buy one of these lowers and create a weapon for themselves. Given all of the laws surrounding firearms, one might find it hard to believe that 80% lowers aren’t heavily regulated.

Bureau of Alcohol, Tobacco, Firearms and Explosives (BATFE)

It shouldn’t come as a surprise to anyone that the ATF covers all of the legal issues behind firearms. For this reason alone, they are immediately involved in the production and sales of 80% lowers. So, what is their policy on 80% lowers?

The long story short is that 80% lowers are federally legal. However, they must meet a few criteria, which we will get to momentarily.

A true 80 percent lower does not meet the criteria of a firearm as laid out by the ATF and in the Gun Control Act. The lower receiver or frame is not considered a firearm until the fire control cavity has been milled. Since this area is completely solid when they are sold (as long as it’s a true 80% lower), the 80% lower or frame doesn’t constitute a firearm in the eyes of the ATF. It’s nothing more than a shaped hunk of metal.

The lower becomes a firearm once you mill it out. This is laid out on the ATF’s website, if you’d like to read it for yourself.

One note on milling the 80% lower is that you must do it yourself. Prior to a recent ATF ruling, you could have a gunsmith or a metalworker mill the lower for you. However, following this new ruling, you must machine the lower yourself. In some ways, this was the first attempt to try and restrict 80% lowers, because not everyone has the skills or tools required to machine a lower for themselves.

Making a final weapon from an 80% lower is also fully legal. It only becomes an issue if you try to sell the weapon or give it to someone else. As long as it is for personal use, you don’t have to put a serial number on the weapon, and it’s absolutely legal to make a weapon from the lower.

State Laws

As with many federal laws, individual states can add to or have completely separate laws. Such is the case with 80 lower receivers and many weapons in general.

For example, if you are building an AR-frame weapon from an 80% lower receiver, you need to check on your state’s laws revolving around “assault weapons.” Yes, we understand that “assault weapon” is a silly term, before someone jumps down our throats about it.

Essentially, you need to know your state laws. If your state has restrictions on magazine sizes, collapsible buttstocks, pistol grips, etc, your completed weapon needs to be in compliance with those laws. Similarly, if you are making a handgun from an 80% frame, it has to be in compliance with any local laws.

However, there are some areas where there are added laws about 80% lowers. For example, in California, you must now add a serial number to the weapon. Basically, this falls back into knowing your state’s laws.


As you can see, the laws are pretty simple revolving around 80% lowers and 80% frames. Right now, they are federally legal. But, as to be expected, these laws can constantly change. It’s important to stay current on these laws, before you wind up in trouble.

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, 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.