An 80% lower receiver is a piece of material (Aluminum) which has been partially completed to a certain point. With readily available tooling from local hardware stores and the right techniques, the lower can be transformed into a working firearm.
Is a 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:
You can legally own the firearm in question in the state in which you live.
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 an 80% lower jig set which we stock for your convenience. The jig helps ensure that the 80% lower is properly machined and that high tolerances are initiated and maintained.