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80% Lowers for Beginners

80 Percent Arms   |   Jan 11th 2021

80% Lowers for Beginners

What now seems to be like a lifetime ago, it used to be that when you were in the market for a new rifle you would simply drive over to your favorite local gun store to get what you need or browse their inventory if you hadn’t made up your mind yet. As we currently live in a Covid-19 world, a trip to the gun store may be a luxury that not all of us can afford anymore for a variety of reasons. Thankfully, we still have some alternative options. If you want to wait in long lines to buy a stock rifle, no one is stopping you. But if you want a more personalized experience, then building an AR-15 using an 80% lower is the way to go.

If you are new to the world of firearm building, then an 80 percent lower may seem foreign if not daunting even. Allow us to guide you as you learn all about lower receiver billets and how to turn them into your next favorite firearm.

What to Consider With 80% Lower Receivers80% lower

Unlike buying a gun, building one requires more finesse, the right tools, and patience. Here are a few things to consider with building 80% lowers.

80 Percent Lower Tools

Quick review: an 80% “lower” or “receiver” is an incompleted item that requires further manufacturing processes to be completed by the end user. When you buy one it doesn’t mean you have a firearm just yet, as it is unfinished and requires about 20 percent of fabrication work left for you, the buyer, to do.

To complete an 80% receiver, you need the appropriate tools. No, your screwdriver set and household hammer will not suffice. We are talking about specialized equipment.

It would be best for you to purchase a complete jig kit, which would include the correct drill bits and a guide to cut and mill the 80 lower to completion. Here’s a list of all the tools you’ll need:

  • Vise—You’ll need to havethis anchored down and to use one with at least 2 inches of jaw width length.
  • Jig—Using this platform, you’ll mount the lower receiver you’ve purchased to it so that you can mill out the internal area of the receiver in a stabilized environment.
  • Jig Router—This is the power tool you’ll be using to mill out the receiver.
  • End mills—Used to cut sideways and is connected to the jig router.
  • Drill bits—Used to bore straight down and through the receiver, also connected to the jig router.
  • WD40—Spray generously in between passes on the area you’re cut and use to lube drill bits and end mills.
  • Safety Gear—Lots of material will be flying around so make sure you have full seal eye protection, ear protection as it can get quite loud, and tough gloves to protect your hands.

80% Lower Materials

Like almost everything to do with firearms, 80% lower receivers come in a variety of materials. The two primary types of materials include aluminum and polymer. In some states, the polymer is banned, but aluminum is not. So be sure to do your research and figure out what’s best for you to purchase.

If you select an aluminum lower receiver, you have a few more choices to consider.

  • Billet — A mid-tier lower receiver that is relatively cheap yet reliable; is relatively easy to work with but can take first-timers a longer amount of time to complete.
  • Forged — A forged lower receiver is top-tier. It is mil-spec, slightly more challenging to cut and mill, but offers greater reliability.
  • Cast — A cast lower receiver is not very popular. If the manufacturing process goes wrong, the cast endures air pockets, which can crack the rifle.

Phases of AR Building

Most firearm builders break down the AR-15 construction process into stages: milling, installation, and assembly. By breaking down the process into stages, builders find the process more manageable and easily organized.

The milling phase involves the jig and jig kit, along with specialized tools as mentioned above like a jig router. The installation phase involves the critical components of the rifle, including the firing pin, trigger and bolt carrier group. And lastly, the assembly phase puts the finishing touches transforming what started out as your lower receiver into a functioning AR-15.

80% Lower FAQs for Newcomers

We are sure you have questions about 80 percent lower receivers and AR-15 construction, so we will answer a few here for you. If you have any other questions be sure to let us know via email or social media!

Do I need a license to build a firearm?

a jig to build a firearm


No, you do not require an FFL license to make a firearm for personal use. If you intend to build an AR-15 and sell it or open a business constructing rifles, then yes, you do need an FFL license.

Are 80% lowers legal?

In most states, yes, 80% lowers are legal. A few states, including New Jersey and New York, ban 80% receivers and gun parts to residents. If you’re unsure, check your local and state laws before purchasing a blank receiver.

Do I need to serialize my lower?

No, you do not need to serialize your lower. At least, notin most states. California does require you to apply for and engrave a serial number on your rifle. This is the act of registration which we will leave up to your discretion whether you choose to do so or not.

unserialized 80% lower

Are there other types of 80% lower receivers?

Absolutely! The 80 percent lower industry is booming. There are AR-15 80% lowers, AR9 80% lowers, LR-308 80% lowersGlock-Style 80% lowers, and 1911 80% lowers. You have plenty of options when building a firearm.

Is it hard to complete an 80% firearm?

No, absolutely not. It can be intimidating at first but if you follow the directions, work with the proper tools, and take your time, completing an 80% firearm is a simple and fun experience. You can find our fantastic how-to guides online that walk you through the process step-by-step.

Now, with a better understanding of 80% lowers, do you feel comfortable building yours? If you’re ready, we have 80 percent lower receivers ready and waiting for you!