So that means sawed-off shotguns are legal? Fully automatic weapons are legal? RPG launchers are legal? Good luck with enforcing that.
The state has its own laws about these matters. I do not see any problem with them refusing to enforce federal law on them. Machine guns were easily purchased before 1932 and were an insignificant problem, most of which was with guns stolen from the government.
Having short barrelled shotguns and rifles illegal only makes sense if you make handguns illegal. Otherwise it is simple stupidity. Rocket launchers were legal until 1968, and we had no problems with them.
What is your point? That ATF will attempt to enforce the federal laws? Possible, but much of this effort is an attempt to push a 10th amendment test case. It may well not work. I have little faith in Roberts or Scalia.
Why shouldn’t all weapons be legal? Men can kill with their bare hands so we should make hands illegal? Punish the crime, not the ability to commit a crime.