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80% Lower Receiver vs Completed Lower Receiver: What’s the Difference?

Even avid shooters and firearms enthusiasts can be unfamiliar with every single topic in the gun community. One particularly nuanced and yet often overlooked niche of the gun community is the expanding popularity of building an AR-15 from an 80% lower. An 80 lower allows what will become a functioning lower receiver for your AR build to be shipped directly to your home without any FFL paperwork. You can buy by 80 lowers by the dozen if you want, and when you are ready to build another AR, just pull one out of the closet and get to work. Sounds enticing, right? Let’s walk through the differences between a completed AR-15 receiver and an 80% lower receiver. Here is a glossary of terms. Brush if you’re not familiar. We’ll be using them a lot.

An 80% Lower is NOT a Firearm (Yet)

In 2018, the gun grabbers are pulling out all the stops to go after the 2nd Amendment. They shouldn’t be surprised that the gun community has responded with equal innovation and creativity. A complete AR-15 lower receiver comes with all the guts inside and it can go “boom”. You can pull the trigger and it is considered a firearm. If one were to arrive at your door you should be able to just slap an upper receiver on it and go to the range. That’s why the ATF classifies a completed AR-15 lower receiver as a firearm and you have to go through an FFL dealer to get one. Even a stripped lower receiver is considered a firearm because it could have a trigger installed at any time. This is not so with an 80% lower. Therefore, it ships straight to your door. No paperwork, no background check, no waiting period, nothing. It’s not a firearm!

Black 80% Lower Fire/Safe Engraved (1-pack) & Easy Jig Gen 2 with Tooling

Our 80% Lower and Easy Jig Kit ships with everything you need to machine a complete, stripped AR-15 lower receiver – all you need is a drill and router!

A Completed AR-15 Lower Receiver Contains a Trigger Group

That’s because the 80% lower is not functional. It can’t go “boom”, it has no trigger or hammer or sear, it can’t even have one installed. So, legally, it’s an aluminum paperweight. The gun community is creative but when it comes to naming products, we keep things simple. With an 80% completed lower, the fire control recess area – the area that houses your trigger group – remains a big, solid hunk of metal. It is inoperable as a firearm and the only way it’s injuring or killing something is if you throw it hard enough. That’s why the ATF does not classify an 80% lower as a firearm and that’s why you can have a 10, even 20 of these lowers shipped to your front door without a single piece of paperwork. Our 5-count pack of 80% lowers is so popular for this reason. It’s just convenient.

So You Bought an 80% Lower, Now What?

You might be asking what one needs with a box full of useless hunks of metal. Fortunately, it is also not 100% legal to own gunsmithing tools like these jig kits. Yes, they too can be shipped right to your front door. With these kits you have the ability to finish the 20% of machining needed and voila, you now have a functional, stripped AR-15 lower receiver ready for all the guts. Only once you complete the milling process is the 80% lower now considered a firearm and only then is it subject to any laws in your state. Prior to that, as far as the government is concerned, an 80% lower is no different than tin foil.

Machining an 80% Lower is 100% Legal

Beyond providing the joy of being able to craft your gun as you see fit through every step of the process, knowing how to complete an 80% upper ensures no one will truly ever be able to stop you from owning a firearm. Namely, because you can create that bad boy yourself. Certainly, the gun grabbers will likely adapt and find some miraculous way to ban big hunks of metal, but until they can classify rolls of tin foil as firearms, we say load up on 80% lowers. The rest of the black rifle community is already in the process, and that’s why they are frequently out of stock.

5.56 (16" Barrel & 12"M-Lok Handguard) AR-15 Upper Assembly

Our complete, ready-to-shoot AR-15 uppers include a BCG and charging handle but are also NOT considered firearms. You can order one and have it shipped right alongside your 80% lower, jig, and tools!

Get the Lower, Get the Tools, Get to Building

If you see any at the link above and you are ready to make the leap we say grab them while they are hot. So there you have it. A completed lower receiver is a receiver ready to shoot and requires the standard paperwork if you’re buying it, not building it. An 80% lower is a big hunk of metal that, with the right tools and a little elbow grease, can be easily transformed into a quality AR-15 lower receiver – and you’re the proud builder who saved a lot of cash doing it. Besides the lower and the jig, you’ll only need a lower parts kit


DISCLAIMER: If you are new to the world of DIY gun building, you likely have a lot of questions and rightfully so. It’s an area that has a lot of questions that, without the correct answers, could have some serious implications. At AR-15LowerReceivers, we are by no means providing this content on our website to serve as legal advice or legal counsel. We encourage each and every builder to perform their own research around their respective State laws as well as educating themselves on the Federal laws. When performing your own research, please be sure that you are getting your information from a reliable source.


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