It can be difficult to choose your first 80 percent lower. After all, you need to consider three different calibers, two types of manufacturing processes, and the legalese and steps needed to complete your 80% lower into a finished AR-15 lower receiver. Here’s a convenient 80 Percent Lower Buyer’s Guide to help make the whole project a little less confusing!
First, What’s an 80% Lower?
An 80% Lower is an AR-15 lower receiver that is not yet completed nor functional. You must complete the last 20%, which is completed using an 80% Lower Jig, and some basic hand tools (a drill press and handheld router).
Is Building an 80% Lower Legal?
Yes, in all 50 states! The ATF clarifies that it’s perfectly legal to build a firearm at home – if you don’t intend to sell it. You don’t need any paperwork. If you can legally buy and own a firearm, you can build an 80 lower!
Some local and state laws require that you submit paperwork or adhere to certain serialization standards, before building. Check all your laws first and consult with an attorney to ensure you’re building legally, if necessary.
80% Lower Materials: Billet, Forged, or Polymer?
80% Lowers are made from three distinct materials: 6061 T6 billet aluminum, 7075 T6 forged aluminum, and weapons-grade polymer. Each has its own, subtle set of advantages and drawbacks, so let’s break ‘em down:
6061 Billet 80% Lower: These bad boys are the most popular 80 lowers on the market, and for good reason – they’re the easiest to build! Billet aluminum is a relatively soft material when it comes to metalworking. It’s also forgiving when minor mistakes are made.
7075 Forged 80% Lower: Forged 80 lowers are made from the same stuff the US Military uses in its service rifles. Forged lowers are more difficult to machine, taking more time with less forgiveness. They’re also more rugged and can take real abuse.
Polymer 80% Lower: Polymer lowers are a niche in the build-a-gun market, favored by a smaller community who want the lightest rifle or pistol possible. Polymer lowers are technically the easiest to machine, though even slight mishaps can make the finished lower unusable.
*Warning: Cast 80% Lowers: Some makers offers cast aluminum 80% lowers. These lowers have historically proven to be dangerous if machined and used. Casting weapons parts can often lead to air pockets and small fractures in the finished component. These imperfections can cause explosive mishaps. These lowers must be avoided.
80% Lower Calibers and Types:
80% lowers are available for a plethora of rifle and pistol configurations. Available calibers include good ole’ 5.56 and .223, while newer offerings include .300 Blackout and classic 9MM. Of course, the land of the .308 AR gets its moment with lowers available that fit the Gen 1 DPMS Platform.
AR-10 80% Lowers: This is an important thing to note if you wish to build a. 308-chambered AR from an 80% Lower: The AR-10 and .308 DPMS platforms are different. Parts are not interchangeable, though lowers now exist for both. We currently offer all Gen 1 DPMS .308 AR components for your 80% build!