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Finishing an 80 Percent Lower: Overview & Tools Required for Success

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The AR market has steadily grown over the last 10 to 12 years. Building and assembling AR-15s as a hobby has grown significantly as well. Most people shop online for their AR-15 parts. You can order almost every part online shipped directly to your door. The only part you cannot have delivered to your door is a “completed/finished lower receiver”. A completed/finished lower receiver is considered the actual firearm and requires a Federal Firearms Licensee to receive and transfer to you.

That is until 80 percent lowers hit the market. (And they hit it hard.)

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What is an 80 Percent Lower?

By Federal Law, an 80 percent lower is just a chunk of metal, and nothing more. The technical term for an 80 percent lower a “receiver blank”. In reality, an 80 percent lower is 80% completed. The area where the fire control group would be installed still needs to be milled. Because the area still needs to be milled, the 80 percent lower is not considered a firearm and is not subject to regulations regarding firearms. Meaning simply, it can be shipped directly to your door.

By law, you can make your own firearm legally. So these 80 percent lower can be turned into 100% receivers. The process to do so is not complicated but does require some very essential gear. So what do you need to complete your own 80 percent lower?

The 80 Percent Lower Itself

There are a lot of different 80 percenters out there made by a lot of different companies and made from a lot of different materials. Our 80 percent lower are made from 7075-T6 aluminum, anodized black, and available with the fire and safe positions engravings. It’s the closest to Milspec you can get with an 80 percent lower.

Our best-selling 80 lower is only $69.95 and can be found here: 80% Lower Fire/Safe Marked (1-pack)

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You Need an AR-15 Upper Assembly

An upper assembly isn’t considered a firearm so it can be shipped to your door, and nothing needs to be finished. A complete upper assembly is your barrel, bolt carrier group, fore-end, and the actual upper receiver. You can assemble one yourself, or buy a complete model ready to attach to a lower. You have a lot of options to choose from when it comes to upper receivers, including different calibers.

Check out our AR-15 Upper Assemblies here: AR-15 Upper Assembly

80 Lower Jig and Tooling

An 80% lower jig and a set of tooling are absolutely required when finishing an 80% lower. An AR-15 jig is basically a device that shows you where exactly to mill out your 80% lower and has guides built in for your drilling/milling. A jig varies depending on the method you choose to complete an 80% lower, and the type of receiver you use. 

We offer a wide variety of 80% lower jigs and tooling that can be found here: 80% Lower and Jig Sets

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Milling Tools

Finishing an 80 percent lower requires a tool to mill the fire control group area of the 80% lower. You can do this a few different ways.

Drill Press

A Drill press is a standing machine that is very precise and accurate. Using a drill allows you to set limits on how far the drill can go. This is a valuable tool that allows precise milling. The downside is it’s expensive and takes up a lot of room.

A Router

A router is a more affordable, but effective option to mill an 80% lower receiver. Combined with the proper jig, it is impossible to go too deep and wreck your lower. A router is easy to store and really no bigger than most electric tools.

The Porter Cable model is one of the best for finishing a lower, it is available here: Router for 80% Arms Easy Jig

Hand Drills

Hand Drills are the most affordable, most common, and accessible method to finishing an AR-15 80% lower receiver. Hand drills are also the most difficult to use, and the easiest to screw up a lower with.

Drill Press Vise

If you are going with a drill or drill press you will need a vise. A drill press keeps the lower receiver from bouncing around as it is milled. It keeps this nice and straight and is certainly a necessity. Our simple, affordable and reliable drill press is perfectly sized for to make a complete 80 percent lower: Drill Press Vise.

Pro Tools

Roll Pin Punches are one of the handiest tools an AR-15 builder can have. They don’t come into play until after you complete your 80 percent lower. Once you start installing your lower parts kit, these things are a godsend. Without them you stand to damage and ruin your roll pin punches, which can then be jammed at worst and just broke at best. They make roll pin punches in a variety of sizes, and an AR-15 uses specific sizes. Our set is specifically made for the AR-15 and can be found here: AR-15 Punch Set Roll Pin Punches.

Finish it

Completing an 80% lower is easy to do with the proper tools. It’s also rewarding, fun, a little stressful, but the farthest thing from impossible. Just remember the important tools necessary to do the job and you’ll succeed.

For further information about the complete list of tools required to finish an 80 percent lower, please check out our: New Armorer's Tool Checklist


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