I don't trust the courts to help us, but the ATF backed down from a previous case about ghost guns when the defendant started questioning the definition of a receiver. Since neither an AR lower nor upper contains the bolt and fire control group, they are not definitionally firearms when seperate. The same goes for every semi-auto pistol frame.
That part of a firearm which provides housing for the hammer, bolt or breechblock, and firing mechanism, and which is usually threaded at its forward portion to receive the barrel.
I don't trust the courts to help us, but the ATF backed down from a previous case about ghost guns when the defendant started questioning the definition of a receiver. Since neither an AR lower nor upper contains the bolt and fire control group, they are not definitionally firearms when seperate. The same goes for every semi-auto pistol frame.
-Title 27, Chapter II, Subchapter B, Part 478, Subpart B, §478.11