Finishing an 80% AR Lower Receiver – Part 1, by 2A Advocate

Editor’s Introductory Notes: This is a three-part article.

Consult your state and local laws before buying any 80%-complete lower receivers.

Proceed with caution. Remember the eternal rule of machining:  You can take metal away, but you can’t put it back.

I recommend buying the Easy Jig 3. Or, if you plan to complete a large number of lowers, then invest in a Ghostgunner 3. Once you’ve completed all of your lowers for your family, you will probably find a private buyer who is willing to pay you 90% or more of your purchase price for your Ghostgunner. The advantage to him will be that he is buying it with no paper trail.

With the 2020 presidential election just weeks away, it seems timely to revisit the subject of finishing an 80% complete AR lower receiver. There have been nice articles in SurvivalBlog relating to this subject in 2014 by JAG  in 2017 by Tupreco, and in 2018 by Hugh Latimer. There are new laws and tools to discuss since these articles have been written.

What are we talking about?

An 80% lower receiver is an unfinished version of a stripped 100% finished lower receiver. It is not a firearm, it cannot be used to fire a projectile without significant machining operations, it doesn’t have a serial number, and it can be shipped directly to your home without a background check or going through a dealer who possesses a federal firearms license. There is no FFL transfer fee. You get the privilege of doing the mechanical work on this chunk of metal or plastic to make it a functional firearm.

Why bother?

It takes quite a bit of planning and time to complete this project. You will do research into materials needed including the 80% lower receiver itself, tools to do the machining, lower parts kit to make the lower fully functional, a barreled upper receiver, bolt carrier group and charging handle. You will read all the instructional materials that come with your jig and watch videos from the jig manufacturer and others who have kindly recorded their experiences and given their assessment of their project for your benefit. The cost of doing this is not insignificant. So, what do you get out of it? You have the basis for a very flexible firearm that has bypassed the usual paperwork trail; a firearm that has never been registered or purchased subject to a background check. You learn a new skill, not only to build this firearm, but you learn how to install and remove parts and repair and replace parts if something breaks or isn’t functioning. You will have pride in building a high-quality firearm that can last potentially for generations. You may be able to build a custom firearm not available commercially at any price.

Who can do this?

You are entitled to build a firearm for your own personal use without being licensed as a manufacturer if you have no intent to sell or distribute the firearm. People have built their own firearms for generations. There is no limit to how many you can make for your own personal use. It is required that you have your own tools and equipment to accomplish the machining tasks. You cannot borrow the tools, or have a build party where everyone comes and shares a CNC machine, or build one for someone else.

Don’t do this if you are prohibited from owning or possessing a firearm for any reason.

The election cometh

Prior to the last couple of presidential elections, gun sales have risen. This year we’ve seen it again, dramatically. There are significant shortages of firearms, firearm parts and ammunition. Demand for 80% lower receivers has also risen, along with some of the tools needed to finish them, and parts to finish a complete AR rifle or pistol. These 80% lower receivers are on the target list for the anti-Second Amendment gun grabbers. In the usual manner, these are vilified and called “ghost guns”. Must be because ghosts are really scary! Several state laws have been passed to ban sales of 80% complete receivers.

California requires you to apply to the California Department of Justice for a background check and serial number, which must be engraved on the lower receiver prior to machining. Connecticut also requires a background check and generally prohibits the sale or transfer of unfinished frames and lower receivers without serial numbers. Same with New Jersey, Rhode Island and Washington, D.C. They can’t be shipped to New York either.

There is huge pressure mounting on Congress to take some action on 80% receivers. The American Bar Association and Bloomberg’s group have long papers urging action. A bill was introduced in July in Congress: H.R.7468 – Stop Home Manufacture of Ghost Guns Act of 2020. This regulates machines that could be used to finish lower receivers. They are targeting CNC machines and 3-D printers. How about jigs and routers?

Folks, I know we have heard many times that the sky is falling, but you have to develop your own opinion of what new restrictions could be on the horizon in 2021. There is mounting pressure for action at the national level. It could be requiring serial numbers, banning their sale or import, background checks or more. Watch for news or actions over the coming year regarding actions taken to further infringe on the Second Amendment at both the federal, state and local levels! You might want to consider ordering lower receivers and tools now, as many are backordered, and have them on hand before 2020 ends.

What does it take to get started?

First, you need to purchase your 80% complete lower receivers. Choices include the AR-15 platform (5.56 x 45mm, .223, and many other calibers), AR-10 (7.62 x 51mm, .308, and many other calibers) or AR-9 (Glock compatible). They can be 6061 or 7075 aluminum or polymer. Some are raw silver aluminum, anodized black aluminum or cerakoted in many different colors. Some are billet and some are forged.

Prices on AR-15 lowers run from about $40 for uncoated, to up to $100 for black anodized and $130 for cerakoted. AR-10 and AR-9 lowers typically run about $30 more, each.

Next, you’ll need tooling and safety gear. I am going to review the use of the Easy Jig 2 from 80% Arms. The multi-version which will do the three types of lowers mentioned above, was priced at $290. Add to that a kit of drill bits and an end mill for $50 and extended drill stabilizers $30. For this project you also need a router, around $100, eye and hearing protection, and a few miscellaneous things like painter’s masking tape and lubricant. And a corded 3/8” or 1/2” variable speed electric drill.

80% Arms and 5D Tactical just introduced new jigs called Easy Jig 3 and Router Jig Pro Multiplatform, respectively. They look very similar to each other and are both priced in the $290 – $300 range and also require a $50 proprietary end mill. There are now videos of the Easy Jig 3 and the Router Jig PRO Multiplatform on their websites. You can see the difference between these and the Easy Jig 2. Refinements have been made and the setup and milling are slightly different. The tools used besides the jig and end mill are the same. Unfortunately, these are both backordered up to 8 weeks at the present time. (Be aware that when looking at the Easy Jig 3 in the 80% Arms website, that the reviews currently posted are for the Easy Jig 2). There are other jigs on the market, and some of them are less expensive.

For completeness I’ll mention that there are CNC machines that automate much of the finishing process. The newest CNC machine I’m aware of is the Ghost Gunner 3 at Defense Distributed, priced at $2,200.

Another method of finishing lower receivers is to use a drill press and milling table that allows movement in the x and y directions, where you move the lower receiver in its jig across a fixed position end mill. Pricing on this method varies greatly, but quality equipment is very expensive.

My decision to proceed

While I have experience with hand tools, drills and saws, I did not have any experience machining (milling) metal. As I looked at the options and the results people achieved with the various methods of finishing an 80% lower receiver, I decided that the Ghost Gunner machine was too pricey, and I was very concerned about using my drill press to do the milling steps.

Looking at several videos on using the Easy Jig 2, both from the manufacturer and YouTube reviewers, led me to believe I could finish my lowers with the best possible results using this technique. There is no question that it is more expensive to finish an 80% lower receiver than to buy a stripped 100% finished receiver. You certainly have money spent on tooling and many hours of research and labor invested. I was worried that I would mess up at the beginning and damage or destroy the receiver. I did make a few mistakes and I’ll share them with you so your project will go even better than mine did. However, all the receivers I finished worked well when the lower parts kits were installed. The areas milled out look so nice, I had people ask who did the milling for me. It’s actually hard to believe it can look so professional even on the first attempt.

The following is a review of the Easy Jig 2. I have no relationship with 80% Arms other than being a paying customer. I liked the product very much. Their documentation is great. I read everything that came with the jig several times, watched all the videos I could find, and followed each step as meticulously as possible. I stopped after each step and reviewed the documentation as I proceeded. There is no award for doing this fast. Working slowly and meticulously results in the best final product. The education I received and the high-quality finished AR-15 lower that may last for generations – that’s priceless!

Please don’t read this review and think it is complete information to do this project. I will hit the high points and give you enough overview to decide if it’s in your purview to tackle this project.

(To be continued tomorrow, in Part 2.)


  1. Completed my own personal batch of lowers a couple of years ago, just as our CA “registration but not registration” law was about to become effective. I joke about the hashtag because CADOJ says it isn’t “registration”, but when you’re required by law now to inform them of your intent to finish a receiver, undergo a BGC, and wait to be issued their own serial number, how can it be anything else?

    I completed some full AR builds, and placed the remaining finished receivers in the safe. Since then, with the increasing likelihood of BGCs for mere parts(!) looming on the horizon, I’m stocking up on the small things like pins, springs, triggers, and of course (with last year’s Freedom Week) lots of full capacity mags.

    1. I had a friend point out this article to me. It is the August issue, pages 16-17, written by Clayton Cramer, who writes lots of articles. I emailed him July 29, 2020 with this message:

      Mr Cramer:

      Thank you for answering so quickly!

      Early in the article you state “It is lawful for Americans…to make one firearm for personal use.”

      and “You are allowed to make only one.”

      Would you kindly forward your source for these statements? I have been looking into this subject and note that intent is a key factor in determining whether an individual is considered a manufacturer who would need to be licensed, or just an individual making a firearm for his own personal use. But I have not seen any information limiting the individual to one or for that matter any specific number of personally manufactured firearms.

      What entity is allowing me to produce only one firearm? Federal? State? Is there a law or regulation? I see nothing about this on the ATF website?

      I thank you in advance for your reply and for helping me clarify this subject.

      Here is Mr Cramer’s response:

      “You are correct, you can make as many as you want as long as you do not sell or distribute. If you don’t sell or distribute, I doubt BATF will notice that you made 1000.”

      Be careful who you listen to; there is a lot of misinformation out there on this subject!!!!!

  2. You are wrong when you said you cannot “borrow the tools, or have a build party where everyone comes and shares a CNC machine”. As long as you do ALL of the work, machining/drilling holes on the lower, it’s completely legal to borrow or loan out the jig, drill bits, and/or router, etc. What you can’t do is ANY machining or work on another person’s 80% lower. Also, there’s no restrictions on how many rifles you can build using an 80% lower and parts, as long as they are not sold, gifted, or traded.

    1. That may be technically correct at the Federal level, but the California DOJ has attempted to prosecute some folks for this. Be sure to check your state and local laws, folks!

  3. I must be missing the point why build a lower with tools that cost at least $1500 to $2000 that could be made illegal in either a Blue State or nationally if Harris becomes President?

    I agree with the essay by Mr. Rawles on a government attempt at confiscation of weapons. It will go poorly for them.

    1. Skip:

      Tools required for the finishing technique I reviewed are as follows:

      Easy Jig 3 or similar – $300.00

      Tool Kit (End mill & drill bits) – $60.00

      Router – About $100.00 to $130.00

      Hand drill, vise, and a few miscellaneous items.

      The cost is far less than the $1500 to $2000 you mention above. I think there is likely a ready market to sell these tools after you have finished your lowers if you choose not to keep the tools. However, your point is still valid in that you can just buy a serialized, finished stripped lower with a background check for less cost. Finishing an 80% lower isn’t for everyone.

    2. Skip, the entire purpose for most people is to have a firearm that is NOT listed in any database or on paperwork residing in your local licensed gun dealer’s file cabinet. That’s why Congress calls them “Ghost Guns”. If “they” don’t know you have it, “they” won’t come kick in your door in the middle of the night to take it. If it makes it easier, consider it as a lifesaving measure for LEOs since you won’t feel a need to shoot 0300 intruders.
      As for the possibility of semi-auto firearms being made illegal by a Harris/Biden administration: Are you ready to comply with that? The old adage about only criminals having guns applies perfectly. Most of Europe has strict gun ownership laws but I would bet there are hundreds of thousands of “missing” machine guns and other small arms stashed away in walls and basements – those people learned to pretend to comply but also knew what could happen.
      A smart person might turn in his registered gun(s) under threat of prosecution but have others “they” don’t know to ask for – i.e., the “ghost guns” they fear so much.

      People, we all need to look beyond the obvious on this gun issue. The leftists know that the key to the whole situation is ammunition. A forward-thinking person might have a deep stockpile of materials and equipment for reloading. Or getting ready to go full-Negan with a spiked baseball bat, or a spear, to defend his garden from raccoons.

      One last point. While the initial cost of a GG CNC machine is steep, it is also so simple to use that as long as you have electricity, a laptop to run the code and an 80% lower a child could follow the steps. And, that mill uses open-source code so you can use it for making other small items or engraving such if you wanted. I don’t know the legality of doing custom engraving on someone else’s previously finished lower receiver but it seems like a possible income source, and there is a market with people who might want to personalize their firearm.

  4. I have finished several lowers, and am interested in how people have serialized or etched identifying info on their polymer lowers. Also, how does CA expect the Serial # to be applied?

  5. The 80% rule didn’t stop the ATF from forcing people to put their serial number on Bob Stewart’s 80% 50 cal receivers and kits when purchaced, with the threat of confiscation . If you get anything through the mail, or don’t pay cash, trade or barter, you are being tracked.

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