What is 80% frame?

[Aguila Blanca]

Right now, the law is interpreted as saying an 80% finished frame is not a firearm. But an 81% finished frame would be. Who makes that call? The govt. Proving them wrong requires a court to rule in your favor.

And, as if it needs to be more complicated, it's a moving goalpost.

Many years ago I ran into a guy who sold 80% lower receivers for AR-15s. The ones he sold were aluminum alloy, not polymer. He showed me two -- one that he had sold previously, based on a letter of approval from the BATFE but which the BATFE boys subsequently rescinded, and then a newer model which required some different operations to complete. Apparently the BATFE took a second look at the original model and decided that it was a bit too easy and didn't really represent 20% of the total work needed.

But the new model wasn't the old model with one less operation completed -- the new model included some of the operations that were left to the end user on the original, while now requiring the end user to complete some operations that were already finished on the original. So it's a very fluid situation, highly subjective, and subject to change in interpretation and enforcement even without any changes to the underlying law and regulations.