Last week, I did a bunch of legwork research, asking Class 3 folks about full auto and silencers. What a gigantic pain it is to get these things!!!
Suppressors: not that big a deal (yes, it is an RKBA violation) so long as you can get the CLEO signoff.
Full auto: dawned on me the big issue there is that it's really about buying/selling the RIGHT to own one. You're not so much paying for the item, but for the transferable "right to keep". (A perspective which could make for an interesting move on reprehensible 922(o).)