The issue is Section 922 (some letter) which says it cannot be assembled in a configuration that is not importable. If you assembled a rifle with a certain number of US parts, it becomes US regardless of where the reciever is made. Therefore, an FAL made with an Imbel reciever can have all the evil features if enough parts are US made. This already stands and any FAL currently legal is so only because it has enough US parts. Therefore, as long as you have the correct number of US parts, then you can have a folding stock and a bayonet lug and a pistol grip and a flash hider.
The real joy, of course, is the high-capacity magazine (especially for the M1a or those newer handguns designed after 1994). Let's face it, a bayo lug and flash hider are nice, but not that much needed. If I had to chose between a bayo lug and 10 round magazine or no bayo lug and an unlimited magazine, I'd give up the poker in any day.
Of course, banning the bayolug/flash hider were pretty stupid in the first place (my FAL was just as deadly neutered).
Ash