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5 Things to Know Before Finishing an 80 Lower Receiver

1. Do You Have All the Parts?

There are quite a few parts you need to complete an AR 15. You start with an 80 lower and may not realize just how many parts make an AR tick. An AR 15 build kit is one of the best ways to ensure you have all the parts necessary. An AR 15 is divided into several parts categories, and you’ll need them all. You’ll need an 80 lower receiver, an upper receiver, a lower parts kit, a buffer assembly, a stock, and if you want to shoot your gun accurately and effectively you’ll need a set of sights, and at least one magazine. 

80 lower


2. Do You Have the Right Tools?

You probably know you’ll need a milling tool of some kind, like a drill press. You’ll also need the proper tooling to mill aluminum, any old bit or end mill won’t do. Also cutting fluid is an absolute lifesaver when you start milling, as is a depth collar.

That’s just for milling the receiver. An armorer’s wrench to attach the buffer tube is very nice to have. Roll pin punches are also a delight to have when building the lower receiver. An AR 15 pivot and roll pin installation tool is also quite handy.

3. Forged or Billet?

80 lower receivers come in a variety of flavors which can mostly be dialed down to forged or billet. These is of course how the receiver is made and this does have some effect on your weapon. Operationally there is almost zero net effect.

Forged lowers tend to be both lighter and more durable. However, the durability rating is a mere technicality, as neither will break with normal use. If you started taking a sledgehammer to them the forged would bend a little less.

Billet lowers tend to have a very clean and unique appearance. The lines straighter, tighter, and cleaner. They are heavier, but do look better overall.

4. How Many Rifles are You Going to Build?

Building rifles from 80 lowers is kind of like eating potato chips. You can’t just have one. If this is your first build it’s understandable to be cautious. However, most people keep building and keep buying. Buying in bulk is possible, and is a good way to save some cash. If you are thinking about building multiple rifles or even pistols buying a 3 pack is typically the best way to go to save money as a beginner. 


5. Do You Know the Completion Phases? 

When building an AR 15 you typically do it in phases. It is important as you build you complete each phase in one sitting. The weapon can be completed at different times, but the individual phases should be completed in one sitting.

Phase 1 is milling the 80 lower. This is best done in one sitting because once you get your groove going with milling it’s much simpler and easier to continue. Plus, trying to guess where you stopped can be a pain. For a beginner, it takes about two to three careful hours to finish an 80 lower.

Phase 2 is installing the lower parts kit and buffer assembly into the 80 lower. This step is essentially assembling parts where they should be. However, the first time you do it can be tricky. Expect this portion to last an hour or two with proper tools.

Phase 3 is assembling the upper receiver. Most of the time upper receivers are assembled, but if you choose you can assemble your own. This is not extremely difficult, but can be a challenge. Allot at least an hour, but first timers can take up to two hours depending on rail system, gas block, and other small details.

The More you Know…

Going into an 80 lower build is a lot easier if you know what to expect, and what you’ll need to finish the build. A little knowledge goes a long away once the tools are out. Check out our selection of 80 Lower Receivers and start your build today:



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