I still like Montana's bill more than the others. It attacks the root problem of US Congressional expansion of Commerce Clause law to include anything they want.
A piece of steel, moving from a foundry in one State to another State, is interstate commerce. Once in that other State, whatever happens to that piece of steel is intrastate commerce, unless or until it should then move out of the State.
The feds, on the other hand, insist that once a gun moves in interstate commerce, it is forever more in commerce and they can regulate it.