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Comprehensive Video Tutorial on Milling an 80% Lower Reciever

Comprehensive Video Tutorial on Milling an 80% Lower Reciever

What is an 80% Lower and is it legal?

Some of you may not have heard of an 80% lower and if so, no biggie we’ll explain it real quick.  An 80% Lower is essentially a partially milled lower receiver for a firearm. Most often of the AR type, though not exclusively. As it is not completed it is not considered a firearm and can be shipped directly to your door (No FFL or paperwork). In order to actually utilize it you must finish milling it out with a drill press and/or router. This is absolutely legal and you do not have to register the weapon, at least from a Federal point of view. Please note states have their own set of laws regarding these and it is your responsibility to ensure you are not breaking any laws by constructing your firearm. There are plenty of resources out there to help you check your local laws and we are not lawyers here so you’re on your own with that. 

My 80% Lower Project

If you are like me you may have known about 80% lowers for awhile and just haven’t taken the leap into trying one out. I personally had wanted to build one for years, but was slightly intimidated and just never got around to it. I’m relatively  handy in the garage, but certainly not a machinist or even close so the idea of milling out a receiver seemed like I would likely be throwing money away on a failed effort. I can now tell you that is not the case. The cost is relatively cheap (you can get lowers around 50USD) and you can easily knock it out in an afternoon. The one exception to the cost is I would recommend purchasing or borrowing a good 80% lower jig. This really does make it a straight forward and simple job. Now that I have knocked one out I plan on doing many more, and I think many of you will really enjoy it too. Let alone the prize of building out your custom firearm in the end. 

About the Video Series Below

In the nine videos below I run you through the entire process as I build my first lower. It is worth mentioning again this is my first time doing this. I’m not an expert, nor do I claim to be. That said I believe there is value in watching them (if you want to do one) as I run you through each step of the process and share some of my lessons learned along the way. Please feel free to ask your questions in the comment links below and I’d be happy to help where I can. Likewise for those of you who are well seasoned at this process please feel free to share some of your expert tips with the community below as well. 



Ok  Let’s get to it!

Introduction and Inventory

Setting Up the JIG

Configuring the Router for the milling process

Pilot Hole Explained

Drilling out the Pilot Hole

Final Mill Prep and Shop Vac talking points

Milling out the Lower

Mill review and Trigger Pocket Setup

Drilling out the final Holes

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Modern Warrior Disclaimer: At the Modern Warrior Project we value the benefit gained by leveraging various experts in the field. One of the many ways we do this is by sharing post from a number of guest authors on our site. Like most things our opinions may vary on different topics, techniques, and various other things in which most of us hold deep opinions. While we may not always share the same opinion of any given author we think it is important to let it be heard and let the reader determine their position on any given topic of discussion. Provided the material does not fundamentally go against our values or we consider it to be ‘Bad’ advice we will alway lean towards publication. Bottom line: The opinions and statements expressed in our blog are those of the author unless clearly stated it is an MWP  positon on the given subject. 

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