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AR 10 80 Lower Kit - Using a DIY Kit to Build Your AR 10

Posted by Jordan Vinroe on Dec 23rd 2019

Although many people classify .308 sized guns as AR-10, regardless of which manufacturer's platform they're compatible with, it is incorrect to refer to DPMS (Defense Procurement Manufacturing Services) .308s as "AR-10s." AR-10 and AR-15 rifles are among the most recognized, popular, and widely used guns. They are a top choice for military use, sporting, and target shooting. Contrary to popular belief, “AR” does not stand for “assault rifle” or “automatic rifle,” it stands for ArmaLite Rifle. But before deciding to  build your own AR-10 with an 80 lower receiver, there are a few things to keep in mind.

Man firing AR-10 built from 80 lower receiver

Meet The AR-10

A semi-automatic, magazine-fed, modular, powerhouse of a rifle,  an AR-10 can be built at home, just like an AR-15. Eugene Stoner first designed the, larger, less popular, AR-10 as a combat rifle. The AR-15 came about with a demand for a lighter and more compact rifle model. Never adopted by the United States military, the AR-10 never quite reached the same popularity as the AR-15. Customizing AR-10s with 80 lower receivers is favored with hunters because this rifle is chambered in a full-powered, .308 caliber, round and better suited for long-distance shooting.

The AR-10 Has A Non-Standardized Platform

Unlike the AR-15, the AR-10 is not a standardized  weapons platform. You can take any two AR-15s and most likely their parts will interchange. The same can not be said for AR-10s. Different companies have different variations of the AR-10 design that are not standardized for construction.

There are two main AR-10 patterned rifles to choose from when buying your AR-10 80 lower receiver: the ArmaLite series and the DPMS series. Both will produce a good rifle, but some believe DPMS has a slight advantage when working with interchangeable parts and magazines from other manufacturers.

AR-10 Compatibility Not Guaranteed With Internal Parts

Various barrel and upper receiver designs, for both ArmaLite and DPMS, are a result of different rifle patterns. Whichever pattern lower you choose, compatible parts made by the same company will need to be used going forward. You will not be able to interchange parts between different patterned rifles. If you choose to use a DPMS pattern AR-10 80 lower receiver to build your rifle, you will also have to use a DPMS bolt carrier group (BCG) and barrel. The same applies to the ArmaLite platform.

You Will Need A Specific Jig

Choosing a DPMS pattern for your AR-10 lower receiver will give you more options when it comes to finding parts. To assemble your AR-10 rifle with an 80 lower receiver, a  specific jig that matches that lower receiver will have to be used. This differs from an AR-15. It is necessary to purchase a compatible 80 lower jig for the AR-10 80 lower receiver that you choose.

Parts That Are Only Compatible With AR-10 Lower Receivers

You will be able to swap parts like the safety, trigger, and trigger springs between an AR-10 and AR-15. But because of differences between lower receivers, the following are only compatible with AR-10 lower receivers and can not be swapped between an AR-10 and AR-15:

  • Bolt Catch
  • Takedown Pins
  • Buffer
  • Magazine catch
  • Most Pistol Grips

What’s Different About The AR-10?

The AR-10 shares external and internal similarities to the AR-15, but they are really quite different. Legally building your AR-10 with an 80 lower receiver differs from building an AR-15. Since they are not used in the military, AR-10s are not mil-spec. On the other hand, nearly all AR-15 parts are considered mil-spec (military specification). This means the parts are made from the same mold using the same manufacturing methods ensuring all parts work together, regardless of maker. Besides the buffer tube, nearly every standard AR-15 part can be swapped between AR-15s.

Most .308 ARs are of the more compatible DPMS variety and are referred to as “DPMS compatible.” ArmaLite AR-10 parts are still sold, but they may be a little harder to come across. When building an AR-10 with an 80 lower receiver, slight differences between DPMS and ArmaLite that make them non-compatible with each other include: how well the upper fits to the lower, the different bolt carrier groups, and the headspace for the bolt carrier group.

The Right Parts Are Key

When  building your .308 AR from an 80% lower receiver and using a jig, keep in mind that the major players in the .308 market don’t actually make 80% lower receivers themselves. It is critical to buy the right type of compatible lower receiver that fits. Once you start building your AR-10 80 lower receiver, you will need to stick to the listed compatible part only. This information should be in plain sight on the manufacturer’s website when looking for AR-10 parts.

Man aiming AR-10 built from 80 lower receiver

Ready To Build

Your build will go smoother when working in a clear work station with the proper tools. To help properly guide your drilling and milling, the correct 80% lower jig is mandatory along with other basic tools, depending on if you use a drill press or router-based jig.

When assembling your AR-10 from an 80 lower receiver, you will need the following parts:

  • Lower receiver
  • Buffer, buffer spring, and stock
  • Lower parts kit to include trigger and pistol grip
  • Upper receiver
  • Barrel and barrel nut
  • Handguard
  • Bolt carrier group and charging handle
  • Gas block

The upper receiver will need to be assembled. You can either build it yourself or order a complete upper for ease. For convenience and to ensure all parts are included and work with each other, ordering a  lower parts kit that includes everything is recommended.

Safety First

Completing an AR-10 from an 80 lower receiver comes with a certain danger if you are not a gunsmith. Basic gunsmith knowledge and comprehension of tools are needed to complete this project. Always buy your parts from a  reputable supplier and if you run into any problems contact a professional. Enjoy your build!