What is an 80% Lower? thumbnail image

What is an 80% Lower?

80 Percent Arms   |   Sep 8th 2020

What is an 80% lower? It’s such a simple question in the firearms industry, but it has shaken things up in the past few years. The term “lower” pertains to the lower receiver of a firearm. In an AR15, the lower houses the fire-control group, the magazine well, and the buffer tube (which the stock assembly sits on).

When people talk about an 80% lower, they’re typically talking about an AR-15 lower receiver, which is the most commonly built 80% firearm on the market today. With the right tools and know-how, building an AR-15 using an 80 percent lower is straightforward — a fun weekend project for a firearms enthusiast like yourself!

The Nitty Gritty of an 80% Lower

Let’s get down to brass tacks here. An 80 percent lower is not yet a firearm — not technically or legally, that is. You see, the lower receiver you purchase online or from a local dealership is still a hunk of aluminum or polymer. It is 80% completed, hence the name. To finish your DIY rifle, you must mill and drill the remaining components into the lower and complete the build piece-by-piece.

The good news is, you do not require a Federal Firearm License (FFL), serialization (in most states, please check local and state laws), or registration to build and own an 80% firearm. Of course, you cannot make one intending to sell to your neighbor or members of your community. That is where the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) draws the line. To build with the intent to sell would place you in a manufacturer category, which requires a specific class of FFL.

According to the various laws and regulations governing the firearms industry, the lower receiver is the only piece of a gun that is technically considered a firearm. It is here that you’ll find serialization. In the USA, it's the lower receiver, and it's the same way with pistols. Interestingly, in some countries, it's the reverse, and handgun slides will be serialized and regulated, but the frames are not. 

When buying a completed AR-15 from your local gun shop, you must purchase from an authorized dealer with an FFL, undergo a thorough background check, fill out various forms and paperwork, endure a waiting period, then pay.

With an 80% lower, you add the piece to your cart when ordering online, then checkout. It’s shipped directly to your doorstep. Simple, right?!

Characteristics of An 80% Lower and a Stripped Lower

80% ar15 lower

We already mentioned that an 80% lower is not yet a firearm. It simply does not have the essential components required to operate as a gun. So, what are the differences between an 80 percent lower and a stripped lower? Let’s take a look!

To complete an 80% lower, you must:

  • Drill a hammer pinhole
  • Drill a trigger pinhole
  • Drill safety selector lever holes
  • Machine the fire control group cavity

Here’s what is already prepped for you out of the box:

  • Bolt catch
  • Pistol grip hole
  • Magazine well
  • Magazine release
  • Buffer detent hole
  • Trigger guard pinholes
  • Upper receiver rear lug pocket
  • Front and rear takedown holes
  • Buffer tube threads and housing

As you can see, what is complete is far more than what is left for you to do, hence the term 80 percent lower.

Benefits of an 80% Lower

  • An 80% lower is not yet a firearm and, therefore, not restricted by laws and regulations as heavily as an AR-15.
  • You do not require an FFL to purchase an unfinished lower.
  • When you buy your lower online, it ships directly to your home.
  • There are no extra fees to complete your build, just the parts you purchase.
  • You do not require a background check.
  • An 80% lower requires no serialization.
  • You are not forced to register your DIY AR-15.

How Easy is Finishing an 80% Lower?

Well, it's going to take a bit more work than buying a 100% from an FFL and building from there. But they've been made as easy to complete as possible with patented jig and tooling systems like the Easy Jig Gen 3. You can now finish an 80 lower in about the time it takes to watch the average movie, and you'll have a lot more to show for it as well. And if you ever have any issues, our cusrtomer service team is here to walk you through every step of the process.