From Reason:

A couple of years ago, an “80 percent” receiver I purchased refused to accept parts, let alone chamber and fire cartridges, until my son and I drilled and milled it to completion; that’s because unfinished firearms are not firearms. For a long time, the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) agreed. But, pressured by the Biden administration, the ATF tried to extend firearms regulations to a lot of things that aren’t guns but could, with work, become one. Now a federal judge is injecting some sense, ruling in a lawsuit that bureaucrats can’t just decide that inert objects are guns.