Sorta off topic, but are destructive devices banned (If you have the appropriate tax stamps)?
No.
One of the funnier things about the FSA 2013 was they didn't affect Class III items or DD's.
It would be a violation of the FSA 2013 to mount a grenade launcher on a post 10/1/13 semi automatic centerfire rifle that also had a folding stock or flash suppressor though.