Building An 80% Firearm- Part 1, by Tupreco

Learn the Why and How

The election of Donald Trump is beginning to show concrete steps toward dialing back the Obama administration’s numerous efforts to undermine our Second Amendment rights. How that will continue to play out remains to be seen. Surprisingly though, even on Obama’s watch there were several pro-2nd Amendment (2A) court and legislative victories, including expansion of concealed carry in many states.

Another thing that occurred while Obama was in office was an unexpected but welcome surprise from the ATF. Several years ago, a well-known AR-15 parts manufacturer requested and received the ATF’s formal approval to manufacture and sell, without restriction, a partially-finished AR-15 lower receiver. This receiver would only be legal for unrestricted sale if the ATF approved the exact design where several very specific features remained un-machined or marked in a way that would aid in its completion. This partially-complete receiver (now commonly called an “80% receiver”) required that the through holes for the trigger and hammer pins be omitted and that solid material must remain where the cavity for all of the trigger components would normally be milled out. This new approach was clearly designed to attract buyers who would then complete the steps left unfinished. When finished, it would be a fully functional AR-15 lower receiver.

Many people don’t realize that it has been legal for years to build your own personal unregistered firearm. Up to this point, the practice of making a homemade firearm has not generated much activity or interest for two reasons. First, a home built firearm cannot be legally sold or transferred to another person. Second, building a firearm safely was typically well beyond the skills of most people. However, the approval for sale of a partly finished receiver ushered in a significant change. Now all that would be required to build a quality firearm at home would be a minimal level of machining skills and equipment. Suddenly, making your own unregistered firearm for only personal use just got a lot easier. Virtually overnight, the 80% firearms industry was born and has continued to flourish. It will surely continue to grow, provided it is not eliminated through a contrary stroke of the ATF’s regulatory pen.

This may be the time to take advantage of the opportunity to build your own “ghost gun”, as this type of firearm is often called. For now you can build your own commercial-quality firearm with virtually no paper trail tracking it (presuming you don’t use your credit card or ship to your home address). Michael Bloomberg, George Soros, and the other anti-2A gun control crowd have already begun putting resources together to convince the public and sympathetic lawmakers to restrict or eliminate the availability of the 80% lower receiver. Even with the Trump administration taking the pressure off the Second Amendment, other governmental bodies still have power to act independently. The worst example of this in years just happened in February 2017, when the Fourth Circuit Federal Appeals Court in Virginia overruled its own previous ruling regarding Maryland’s state law banning the AR-15 and other similar scary rifles. The court finding was that firearms of this type had no legitimate purpose other than to kill in large numbers and that these “weapons of war” (their words) did not qualify for protection under the Second Amendment. It was not an actual ban per se, but if left standing it would clear the way for an unfriendly federal government issue, an executive order, or a liberal state to pass a law to ban them. Further, in 2016, four states voted on gun control initiatives, and all passed except for Maine’s universal background check measure. Other laws recently passed in California now affect a firearm built there using an 80% receiver through new restrictions going into effect regarding fees, registration, and serialization requirements. Given these pressures, it seems like now is a prudent time to do your research and get to work before it’s too late.

So what are the things that need to be considered before building your own firearm using a legal 80% receiver? You can legally purchase one at this time and perform the final machining operations to make it 100% functional. If done according to ATF guidelines, the 80% receiver is not considered a firearm by any federal or state agency. Since the ATF approved this approach several years ago, manufacturers and sellers have been popping up rapidly. The AR-15 variants have catapulted to capture the lion’s share of the market. Also available are versions for the AK-47, the 1911 pistol, and most recently, an 80% pistol frame designed to be completed using standard Glock pistol components.

In this four-part article series, we will look at the issues surrounding the purchase, completion, and assembly of three very popular 80% platforms:

  • AR-15 rifle,
  • 1911 Browning-designed pistol, and the
  • Glock–style pistol, in both full-size and compact versions

There is also a smaller but active AK-47 builder community as well plus a growing AR-10 presence. However, we will focus here on the versions listed above, since they are more widely supported and popular. Other than the specific technical issues, the things that affect the three 80% platforms in this series also generally apply to the other platforms as well.


Understand this up front, I am not a lawyer, so nothing listed here may be considered legal advice of any kind. Your decisions should be made after thoroughly researching the law and published ATF guidelines. At the end of the day, it is your responsibility to confirm which aspects of this apply to you and how they apply. There are some very important distinctions about what the ATF does and does not consider a firearm, including at what moment your 80% hunk-o-plastic or aluminum magically and legally transforms into a firearm. At that moment, it comes under the jurisdiction of multiple government agencies that range from your local LEO to the ATF (depends on your locale). For advice, start with the person or company where you might purchase your 80% components. Realize that they are hoping you buy as much as you can from them, so verify what they tell you. Read the links that are provided here and on their websites. Read the actual laws themselves. I can’t stress enough how important this is. You will learn a great deal here, but at the end of the day it’s completely on you.

What is an 80% firearm?

This is the first and most important issue because an 80% firearm as discussed here is not an actual firearm as purchased. It does not become a firearm until an individual completes the steps needed to transform it into a form that does meet the legal definition of a firearm. To be on the safe side, I consider an 80% component a firearm from the moment the first feature is drilled or milled. The reason I approach it that way is that there is very minimal case law at this time. The only configuration that has been specifically designated by the ATF as “not-a-firearm” is the part you took out of the box that is described in the seller’s Determination Letter (more on that later). In other words, once the 80% component is modified in any way from its “as-received” condition, the government may try at some point to declare that it has become a firearm. This can happen any time it suits their purposes to do so. It would then be up to you to spend the time and money proving that it is not a firearm. Who wants to sign up for that? Just don’t plan to sell your partially finished receiver once you start to machine it. The good news is that at this time, a reasonably competent individual can safely fabricate his or her own 80%-er into a functional lower receiver fairly quickly. Once you’ve gathered the correct additional components, it can also be assembled into a usable firearm without restriction and used as you would any firearm.

What is considered a firearm?

We have to start with a working definition. This is where the ATF website is actually a treasure trove of information. Find out yourself at You can find listings of most current federal laws there as well as the ATF regulations that serve to interpret (or some would say, re-write) those laws. Be sure your state laws also allow this kind of build to take place. California is already trying to restrict their large in-state 80% community.

Two of the most important federal statutes that apply are the National Firearms Act (NFA) of 1934 and the Gun Control Act (GCA) of 1968. These two are the source of most of the definitions and restrictions you will have to comply with. That said, here is what the GCA and the NFA calls a firearm:

(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.

The terms “firearm silencer” and “firearm muffler” mean any device for silencing, muffling, or diminishing the report of a portable firearm, including any combination of parts, designed or redesigned, and intended for use in assembling or fabricating a firearm silencer or firearm muffler, and any part intended only for use in such assembly or fabrication.

The term “make” is defined in the NFA to include manufacturing, putting together, altering, any combination of these, or otherwise producing a firearm.

Once something is legally considered a firearm, it becomes subject to a myriad of restrictions and regulations (yes, infringements) that control its sale, transport, purchase, and use.