The 80% lower receiver (like our billet and forged receiver blanks) is one of the easiest ways to build an AR-15. Building at home requires no FFL paperwork or background check, according to the ATF. That means you get to save money. No special taxes, no extra fees, no hassle.
But how do you complete an 80 lower receiver, anyway? The fact that you are the one actually making the firearm – milling and drilling your lower with a jig – is just one reason so many AR lovers are choosing to build their next black rifle or pistol an 80 lower.
If you’ve never attempted to complete an 80% lower, you might think it’s too difficult for you. But the lower can be completed in a multitude of ways, using a variety of tools. And it does not require exceptional skills.
4 way complete an 80 lower receiver
While the average AR-15 builder may not have access to all the tools mentioned here, he or she should have access to at least one or more. These various ways of completing an 80 lower receiver will help you understand what you need or can use to complete your 80 lower.
1. 80 Lower Jig
The 80% lower jig was specifically designed for completing AR-15 receiver blanks! We’re talking about the jig first because it’s probably how you’ll get the job done.
An 80 Lower Jig acts like a miniature milling machine and drill press bench top, right in your garage or basement. The 80 Lower Jig uses individual guide plates and a router attachment plate to drill and mill out the lower’s fire control group.
The best part of the jig is that it does all the measuring for you. The guide plates automatically “measure” the pocket you need to mill, and a drill depth guide even tells you how far you have to go.
Essentially, the jig does all the work! All you need to do is act as the “machine”. You’ll be using a handheld router and a hand drill to complete it.
This only takes around 1 to 2 hours, even 15 minutes for pro builders (using the Router Jig PRO from 5D Tactical, which is considered the fastest jig).
2. CNC Machine
An automated machine tool operated by computer numerical control (CNC) is often referred to as a CNC machine. These computer-aided tools are controlled by computer-aided design (CAD) and computer-aided manufacturing (CAM) programs. By using a CNC machine, the process of completing an 80 lower will be automated and offer precision machining.
For those who have access to a CNC machine, there are various CAD programs available online to complete your 80 lower receiver. These CAD programs will allow you to program the CNC machine in order to complete your 80% lower to MilSpec standards.
Pros: The pros of using a CNC machine are the elimination of human error and precision manufacturing. Once the CAD program is installed and X, Y and Z-axis are established, the CNC machine has the ability to complete the 80% lower with precision.
Cons: The CNC machine will require adequate knowledge of CAD programming and CNC machine operation. Unfortunately, most individuals do not have access to a CNC machine.
3. Milling Machine
A milling machine is designed to machine solid materials such as metal and wood. Depending on make and model, milling machines can either be automated, CAD directed or manually operated. Milling machines are capable of multi-axis machining and offer precision capability even if operated manually.
Pros: A milling machine will offer precision milling of your AR-15. Even with limited knowledge in machining, milling machine basics can be learned very quickly. If you have access to a milling machine, ask the owner to teach you some basics. With just a few basic skills you can complete your 80 lower using the precision milling capabilities of the milling machine.
Cons: Milling machines do require a learning curve. Not everyone will be comfortable learning how to operate a milling machine and its dynamic capabilities may be somewhat intimidating. Depending on your skill level, a milling machine will offer superior capabilities.
4. Drill Press
A drill press is a pedestal style drill that is mounted to a stand. Most portable style drill presses have a spindle and chuck that moves parallel to the axis of the pedestal. Most drill presses will be operated manually, although they will allow for setting of various depths when drilling or milling. The drill press can also provide for the mounting of a vise or clamp in order to securely hold your 80 lower receiver while drilling and milling.
Pros: A drill press is the simplest way to complete your AR lower. With limited knowledge and skills most anyone can complete an 80 lower with drill bits and end mills. The drill press is also economical and most individuals will have access to a drill press.
Cons: A drill press will not provide the precision machining of a CNC machine or milling machine.Although, if done correctly (and by using a drill press vise), most people will not be able to tell your lower receiver was completed on a drill press.