Buy and Finish an 80% Lower…Because They Don’t Want You To

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80% Arms has lowers and jig kits in stock and ready to ship. No one knows how much longer it will be possible to buy these without a background check, so now is the time to buy.

You know you’ve been wanting to try it.


  • The only jig known to fit every known AR-15, AR-9, AR-45, and DPMS Gen 1 .308 lower
  • Converts between AR-15 and .308 in seconds
  • No adapter pieces are required to convert, adjustment is fast and easy.
  • Self centering mechanism ensures perfection even with exotic billet lower designs
  • Tested to work with over 23 of the most common handheld routers
  • Completely compatible with full size routers (adapter required). Click to view list of compatible routers.


  • Less drilling, drill only 1 hole prior to milling
  • World’s fastest jig, can complete an 80% lower in under 30 minutes
  • Jig requires no disassembly of side walls to insert or remove 80% lowers
  • 80% lowers can be inserted or removed in under 10 seconds


  • Built-in measuring gauges. No measuring tools needed
  • No drill press needed, only a hand drill and handheld router
  • Included Shop Vac Attachment means less mess!

It’s fun and easier than you think.


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  1. AS I understand it, completing 80% lowers is, in California now essentially illegal. First they required that a builder obtain and engrave a unique serial number on the receiver prior to beginning the build, with a background check, of course. Now the DOJ says that building a firearm requires a manufacturer’s license, even if one is not a “manufacturer” as defined in Federal law, and they will not issue a serial number without that license.

    • Links, please? I completed my 80%’ers back in 2018 before CA’s silly restrictions took effect in July 2019, but I still have a couple of unfinished frames in the safe. I haven’t heard of the “manufacturer license” requirement.

        • Exactly. Don’t use your gun in a crime, and LE will never have any need to see or know about it. Why is it wrong to simply own something?

          MALUS EST = latin for “It is bad because it is”. This is a natural crime recognized by everyone such as murder, theft, assault, etc.

          MALUS DICTUM = latin for “It is bad because someone says so”. This is the numerous petty laws in which there is no victim, such as crossing a street at an angle, texting while driving, possessing a particular type of gun TPTB don’t like, etc.

      • It depends on what you intend to build. “Featureless” or mag locked ARs are GTG, but a standard AR is an assault weapon:
        § 5506. Firearms for Which No Unique Serial Numbers Will Be Provided.
        The Department will not provide serial numbers for self-manufactured or self-assembled prohibited weapons pursuant to Penal Code section 16590, an assault weapon, a machine gun pursuant to Penal Code section 16880, a .50 BMG rifle pursuant to Penal Code section 30530, a destructive device pursuant to Penal Code section 16460, a short barreled rifle pursuant to Penal Code section 17170, or a short barreled shotgun pursuant to Penal Code section 17180.

        Now I have no actual knowledge on the subject, but I have an understanding that the State has essentially outlawed AR pistols, so those would fall into this category as well. The only exceptions for prohibited weapons are for manufacturers who intend to sell the finished products out of state.

        • California has not outlawed AR pistols in general. This is a myth that has been passed around the Interwebs. I possess some and have been very careful to navigate the labyrinthine maze of laws.

          Mine are equipped with KaliKeys, which make the gun(s) bolt action and negate the State’s definition of an AW, which is any gun that has these three characteristics:

          1. Semi auto action
          2. Detachable magazine
          3. Centerfire cartridge chambering

          Interestingly enough, my Browning BAR deer rifle falls under this definition, so it’s *technically* an AW under CA law, even though it looks and acts like Grandpa’s deer rifle…because it is. So it was okay to own, until it wasn’t. Because Democrats.

          Our laws here are so stupid.

    • Just wait until you do a 0% printed one.
      Parabellum ex nihil.
      It’s truly magical. It makes you want to FaceTime a leftist and chuckle to their tears.

        • Jon –

          I’ve been looking for a suitable spade in pawn shops for an AK-Shovel build.

          Got any recommendations for a suitable parts kit to make it into a finished AK?

    • I purchased these from 80% Arms. They are quality lowers. Still waiting for the jig (4 to 6 weeks they say.

  2. (off topic but may be valuable to some)


    I’m not sure what the general reputation of is, but my recent experience with them was so bad that I felt I should pass it on as a cautionary tale. So here are the particulars:

    1. Day 1:
    – found a rifle on their site. Bought it and added 3 magazines.
    – due to a hiccup I had to reload the page before checking out
    – BofA wouldn’t let me use my card (yah, still being woke), so I used my wife’s card.
    – When I got the final order, it showed my wife as the orderer and included 2 orders for 3 mags each.
    – I called the support line within 15 minutes of placing the order and was told:
    a) no problem with the wife’s name on the order because that was financial info only and
    b) (after checking with the boss) they wouldn’t cancel the bogus mag order because all sales are final.

    2. Day 3:
    – late in the day, I got an email from that said the order for the gun was cancelled without explanation, but in checking the site, the two mag orders were still going through even though one was bogus and the other was useless without the gun.

    3. Day 4:
    – finally got thru to Support late in the morning (it was a Sunday, so they were probably in church praying for forgiveness). The tech said:
    a) The gun sale was cancelled because the purchaser’s name didn’t match the orderer’s name.
    OK, they said that falls under the Feds “straw purchase” thing and I can’t blame them for cancelling, but it would have been nice to get the correct info when I asked the first time (see 1a above) or even an having an edit on the order form that checked before the order was created, not two days later.
    b) Even though I have no use for the mags without the gun, it was too late to cancel them.

    Obviously, I, or rather my wife was on the phone with the credit card company for an hour (and don’t think she won’t get even for that!) cancelling any and all charges from

    I’m not going to tell you not to use them, that’s up to you, but if you do, make damn sure the order is exactly what you want and if one purchase depends on another, you might want to wait until the main one goes thru before you order the next. These folks do not care about reality or customer relations once you click on “Submit Order”.

    • It isn’t a straw purchase thing. It is a company thing. I had Bud’s cancel an order I placed for a pistol for my daughter. I live in California, and the gun was not on the Roster, so it could not be shipped here. But my daughter does not live in California, and the gun was legal where she lives. Didn’t matter. They said their computer system “wouldn’t allow it” even though it was a perfectly legal transaction. (The only issue for the background check is who fills out the form, and who the recipient is, not who pays for it.) I have not had the same issue with other companies.

      • I do know there was a court case in California where the courts said an 80% is not a weapon when they tried to throw the guy teaching people how to make it into an operating lower unit. California had to throw that case out but the ruling was never brought to public light, I wonder why. California will probably loose this battle if brought to the supreme court because in the United States you are allowed to build your own firearm. That’s why the 3d print guns can now be posted again. California has a way of thinking the constitution doesn’t apply in their state. Maybe that is why they are loosing seats in congress, you think.

    • I also had a really bad experience with them.
      I’ll never use them again and I will badmouth those illiterate idiots for years to come.

    • Thanks for the heads up. I’ve never done business with and will not at this point. I have done internet sales for hard to find old, rare left handed rifles through Gunbroker and new ones from Buds in Lexington. Both have been 100 percent reliable.

    • “– BofA wouldn’t let me use my card”

      Strange, I have a BoA (debit) card, and a recent handgun purchase went through just fine…

    • Same. I’d love to do an 80% build…but a simple lower receiver in the raw for $120? A jig (and *only* the jig) for $350-plus? No.

      Hell, I put together an entire AR a couple years ago that cost less than their 80% lower “starter kit.”

      Yes, that was then and this is now, I know…but I don’t have several hundred dollars to throw at a “just because they don’t want me to” project, and that’s just the way it is. My money is going to things like replacing household appliances, buying ammo a couple boxes at a time, bolstering the savings account, and keeping up the food storage and emergency supplies.

      • Come to think of it, our would-be overlords don’t want us to do most of that, either. So there’s your “because they don’t want me to.” 🙂

  3. Spend hundreds extra to build something they don’t want me to when I’m just doing regular builds cheaper that they don’t want me to!?!

  4. The jigs require very specific end mills, whose parameters I’m unable to ascertain. Is there some information out there that tells me what other end mills work with this jig?

    • Marcin Porwit,

      I am not aware of specific jigs calling for specific end mills. Maybe they do–I am not aware of it. (I am by no means an “expert” at finishing 80% receivers and only have limited experience researching and tinkering with such projects.)

      Simple intuition tells me that all you need is a basic router bit which is cylindrical and without any taper or fancy profile. Remember, all you are doing is removing material at a simple right angle to the top surface of the receiver. As long as your router bit does that, I think you are good to go.

      Note: you probably have to drill a pilot hole in the area where you are going to remove material with your router. If that is the case, then your router bit would have to be a smaller diameter than the drill bit which you use to create the pilot hole. Other than that, I don’t see where there would be any other specific parameters of the router bit other than being cylindrical as I stated above.

    • The end mill is designed to run up against the guide without removing material. So the jig can be used over and over. The end mill does wear however and will need to be replaced after so many uses.

  5. I don’t have the mechanical skill or the tools. The tools, I can get, but the skill…eh, I flunked shop class in the 8th grade. So, yeah, I think I’ll let everyone else have fun with the 80% lowers.

    • The Rookie,

      The jigs that companies provide for finishing 80% receivers make the process very straight forward and eliminate the need for “mechanical skills”. If you can follow directions, NOT be in a hurry, and pay attention to detail, you will do fine.

      The only “mechanical skill” that I believe is necessary is having a basic sense of how slow/fast to proceed with a drill/router when drilling/routing. If you go way too slow, things get hot and you may tend to melt the jig. If you go too fast, your holes and routed cavities will be rough and have a lot of prominent machining marks.

      With respect to how fast to drill/route, I would simply tell people to move the drill/router at a speed which produces slow and steady and easily observable progress–and does not cause a huge change in the tone (e.g. sound/pitch) of the drill/router.

    • “I don’t have the mechanical skill ……” Is just a pansies excuse that “guys” give a wife/woman so they can sit on ass watching sports rather than doing ANYTHING useful. Man up. Dive in, fail or not, do over. Start with doing your own damn oil changes. NO freaking excuse Nancy.

      It’s also ok if you break a freaking nail.

      • I’d say skill and ability are very different things. Everybody has the basic ability to do things like this; it just comes down to how much time and effort you’re willing to put into acquiring the skill.

        Some things, though…I did my own oil change. Once. It wasn’t difficult, but like just about all vehicle mechanicking, it was an annoying and greasy job, and I didn’t find it rewarding in any way. I’ll happily pay someone else to do it.

        Some things just aren’t worth DIYing, and the time/effort/reward calculation that goes into it is different for everybody.

        I suspect we’re coming up on times when necessity will be the deciding factor, and people who didn’t develop certain fundamental skills might be SOL. (Depending on which skills those are, many of us could be; time will tell.)

  6. But, But, ATF is going to change the definition of a firearm, and drop the lower as a firearm.
    Right? So maybe we should buy uppers?

  7. You know what’s easier and cheaper?

    Just 3d print a 100% lower.

    The technology is at the point where they’re as durable as metal (remember when people said your Glock wouldn’t last either?)

  8. I don’t know about other states, but in Michigan, any and all 80% builds, once built, are required to be registered. Kinda defeats the purpose…

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