Gnu asked:

And what about the peeps I see on US TV that own AA guns and tanks? Is that all smoke and mirrors?

The AA guns and tanks require permits, and must be "neutered", so to speak. That is, the guns can't fire. Privately owned machine guns are possible too, but have to be essentially destroyed as an actual weapon, or at least for automatic fire.

That's the official position, anyway. However, there are a number of ways to disable the firing mechanism of a machine gun to make it legal. A "collector" may own more than one such "disabled" weapon, disabled in different ways, so that anyone competent can remove the defective/destroyed part(s) from one machine gun and replace it/them with good parts from another weapon which had been disabled in a different way. That change operation wouldn't take the competent gun mechanic more than two or three minutes to accomplish, at most.

Dave Oesterreich