80% AR15 Lower Receiver FAQ

80 Percent Lower Frequently Asked Questions

What is an 80% Lower Receiver?

Technically there is no such thing as an  80% lower receiver or a 90% or 50% etc… The Burea of Alcohol Tobacco Firearms & Explosives (BATFE) commonly know as ATF only classifies receivers as a FIREARM or NONFIREARM. The term 80% came from the firearms MFG industry as a way to classify the percentage of work that has been done to a piece of Aluminum which has been partially completed to resemble an AR15 Lower Receiver.

Is an FFL required to/build a firearm for personal use?

No. You are building the firearm for yourself for your own personal use which is legal under the Gun Control Act of 1968. This is on the ATF’s website under their FAQ page. You can see it here http://www.atf.gov/firearms/faq/firearms-technology.html .

 It is not required to be transferred through a Federal Firearms License Dealer with all the federal paperwork like its finished counterpart, the completely finished lower receiver.  These factors make for easy purchasing for home gunsmiths and hobbyists for personal use.

As long as the following laws are met there are no problems:

  1. You can legally own the firearm in question in the state in which you live
  2. You are building the firearm for your personal use and for yourself only.

It is a good idea to mark your firearm somehow so that should it ever be lost or stolen you have a way to identify it and report its loss to your local law enforcement. Please check your local and state laws.

What tools are required or recommended to finish my lower receiver?

Building an 80% lower receiver into a finished lower receiver can be done using a variety of readily available tools and the proper techniques. The most popular methods involve using a drill press or milling machine. Once you have chosen the type of drill you wish to use, you will also need a 80% lower jig set. The jig helps ensure that the 80% lower is properly machined and that high tolerances are initiated and maintained.


Tools Used:

  • Drill Press (minimum requirements)
  • Drills & End mills
  • 1/2″ END MILL
  •  5/32 Drill
  •  3/8 Drill
  •  3/8 END MILL
  •  5/16 END MILL
  •  5/8 DRILL
  •  5/16 LONG END MILL
  • 3/16 Allen Hex Wrench
  • Cutting Fluid
  • Calipers (For Measuring / inspection)
  • lots of Youtube Videos ( for general understanding)
  • A few minutes of time ( serioulsy Dont Rush it )
  • A few Beers ( to enjoy after complettion )


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