80% Lower Receivers FAQ – Complete Guide [Explained by Firearms Attorney]

by Ryan Cleckner

December 11, 2020



There has been a lot of news and talk lately about the legality of “80% firearms” (often called “ghost guns).

As a firearms attorney representing Federal Firearm Licensee (FFL) manufacturers and FFL dealers across the country, I get a lot of questions about this topic and decided that it would be best to answer them all at once here in a big 80% lower receiver FAQ.

Note: Although I am a firearms attorney, I am not your attorney and this is not legal advice. I will be covering federal gun laws only. You must consult an attorney in your area to understand how your local rules and laws may differ.

Here are the 80% lower questions we’re going to answer:

What is an 80% Lower Receiver?

An 80% lower receiver is an object that has been manufactured to a certain point where is has not crossed the line of being considered a firearm under federal law.

These 80% lower receivers are popular for persons interested in building their own firearm at home because only a few remaining manufacturing steps remain to turn the 80% lower into a functioning firearm frame/receiver.

That’s the simplest summary I can give about 80% lowers – let’s dive a bit deeper to discuss the laws and nuances.

But first, before we can understand how an 80% receiver is NOT a firearm, we need to understand the definition of a firearm.


For the federal definition of a firearm, we need to look to the Gun Control Act of 1968 (GCA), specifically 18 U.S.C. § 921(a)(3)(A-B) which states:

“(3) The term “firearm” means
(A) any weapon (including a starter gun) which will or is designed to or may readily be converted to expel a projectile by the action of an explosive;
(B) the frame or receiver of any such weapon;
(C) any firearm muffler or firearm silencer; or
(D) any destructive device.
Such term does not include an antique firearm.”

From this federal definition of a firearm, we get two very relevant sections for answering the question: what is an 80% lower?

Part (A)

We can see from part (A) that a firearm is an object (weapon) that expels a projectile by the force of an explosion. Therefore, under federal law, pellet guns/air rifles/paintball guns/etc are NOT firearms because there is no “explosion” (even though they clearly expel a projectile).

We can also see language about “readily converted.” This means that a complete firearm is clearly a firearm but also an object that isn’t quite yet a functioning/complete firearm is still legally considered to be a firearm if it can be “readily converted” to become a firearm.

*shakes head*

Said in plain language to show how confusing this is: “A gun is a gun. If what you have isn’t a gun, but you could easily make it into a gun, then it’s also a gun.”

This is where the term “80%” is coming from.


This is a great point to address that “80%” is not a real term/part of the definition – it is simply a marketing term.

Notice that nowhere in the law is there any percentage mentioned. Instead, it only references “readily converted.” This means that if you have a raw piece of material that could become a firearm and it is only 10% completed BUT the part that is complete makes it readily convertible to fire a projectile by the action of an explosive, then it is considered a firearm even though it is only 10% finished.

I bring this up as a point of caution, too many people believe that something is or isn’t a firearm based on its percentage of completion – this is not true. “80%” is merely a marketing term to describe an object that has not yet crossed the “readily conferable” line.

If you’d like to learn more about this nuance and get some help determining when something crosses this imaginary line, you should check out our article on What Does Readily Converted mean?

Part (B)

The second part of the firearm definition that can help us here is part (B) which tells us that the frame or receiver of a firearm is also a firearm by itself.

Think about it this way, if you took a vehicle apart into 1,000 pieces, you don’t have 1,000 vehicles, you have 1 vehicle in 1,000 pieces. Therefore, it is helpful to pick one main component to consider the vehicle: the frame.

The same is true with firearms. The frame (handguns) or receiver (rifles) is usually the main component to which the other components of a firearm attach. The definition of a firearm frame or receiver is found in the federal regulations at 27 CFR § 478.11:

“Firearm frame or receiver. 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.”

From the ATF Guidebook


Now we can circle back to the definition of an 80% lower…

By now, we’ve learned:

  • “80%” is just a marketing term and the percentage of completion has no bearing on the determination of whether an object is a firearm,
  • a complete firearm is an object that expels a projectile by an explosive (boom/bang + flying bullet = firearm),
  • the frame or receiver of a firearm is also considered to be a firearm, and
  • an object which isn’t a complete firearm yet but it could be “readily converted” into a complete firearm is treated as a firearm.

So, an “80% lower” is a product offered to avoid every definition of a firearm above while still being complete enough that it is easy to make your own gun at home.

If you’d like to make guns as part of a business, you’ll need to get an FFL.

Under federal law, these are legal (for now) but some states restrict these items.

Also, the distinction between non-gun and gun (once it can be readily converted) changes based on each firearm type (don’t get us started on ATF’s arbitrary rules) but the ATF has been pretty clear on what parts of an AR-15 lower receiver must remain unfinished in order for it to be a non-firearm:

Is it Legal to Make Your Own Firearm at Home?

Under federal law, it is completely legal for anyone who can possess a firearm to make their own firearm(s) at home.

In fact, we have a guide to making your own glock at home by using Polymer 80 kits.

From the ATF:

Does an individual need a license to make a firearm for personal use?
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.”
References: [18 U.S.C. 922(o), (p) and (r)26 U.S.C. 582227 CFR 478.39, 479.62 and 479.105]

However, please be careful here as some states restrict this activity.

Do 80% Lowers Need Serial Numbers?

No, under federal law, it is not required to mark any firearm you made for personal use at home with a serial number.

According to the law, and its implementing regulations, the requirement to mark all firearms with certain markings (one of which is a serial number), only applies to manufacturer FFLs (Type 07 and Type 10 FFLs).

Therefore, if you’re making the firearm for personal use, there is no federal requirement to serialize it.

Of course, this may change as there has been a lot of political pressure around “ghost guns” (what some call these unserialized firearms). Also, some states have serialization requirements.

Is it legal to sell/purchase a firearm made from an 80% lower receiver?

Yes, a homemade firearm without a serial number can be legally sold or purchased (under federal law).

However, be careful here: you may NOT build a firearm with the intent to sell it without an FFL. You can build it intending to keep it and then later change your mind, however, this can be a very muddy area.

My advice? Don’t sell homemade guns. Make it for yourself and keep it for yourself.

But if you do decided to sell (or buy) an 80% lower built gun, you must complete the transaction like any other firearm. This means that interstate transfers must go through an FFL.

Are “80% firearms” legal in my state?

I’m very hesitant to answer this question because I am unable to keep this article up to date with how fast certain states can change their laws.

You may use this as a guide or starting place if you like but you must not rely only on this information for your state or local laws.

“80% firearms” are effectively banned in these states:


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About Ryan Cleckner

Ryan is a former special operations sniper (1/75 Ranger) and current firearms attorney, firearms industry executive, university lecturer, and bestselling author of the Long Range Shooting Handbook.

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  1. If I have an 80% receiver that was never completed or started for that matter. It is as it came from the seller. Can I, as an individual, sell it to someone else, another individual, that would like to complete it?

  2. Would you happen to know if I can receive these parts in Long Island New York without an FFL

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