It seems every federal law that deals with firearms contains the term "a firearm that has moved in or that otherwise affects interstate or foreign commerce'.
I believe that could be the reason why the ATF has failed to go after the states that have the "Made in X" laws, such as Montana, Wyoming, etc.
It's gonna open up a whole can of worms those laws hold up.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071