I have an M. It is totally legal. It was imported as a sporting rifle because it doesn't have any evil features (except that it accepts a detachable magazine). But that's ok. Just the same way MAK-90's are ok. It doesn't have a threaded muzzle, a bayonet lug, a bayonet, a flash hider, pistol grip, folding stock, illuminated sights, or anything else. It is just an autoloader that takes detachable magazines. The D models have the evil features because they were imported before the 1989 ban.
Note, it is illegal to install a pistol grip stock or a folding stock on this rifle (M models). I see dozens of them on gunbroker being sold like that. It is an illegal modification. It's just one of those things that the BATFE hasn't cracked down on.