What is an 80% Lower?
An 80% Lower is the lower receiver portion of the AR-15 which has not completely been milled out, hence the “80%” portion of the name. The only part that is not completed on an 80% lower is the port which contains the trigger. In this way, the lower is not considered a firearm under the legal definition. And when it comes to the transfer and sale of such lowers, they don’t require FFL transfers or background checks, so they can be shipped much cheaper, and you can receive them much quicker than you would something legally considered a firearm.