If he indeed owns an AK, odds are it's a Dewat.
And if a dewat (DEactivated WAr Trophy), we'd need to
know if it's of the registered or unregistered variety,
and then any local laws that might apply.
So don't go ballistic over this just yet.
It could all be perfectly legal.
Or not.
Not necessarily, if he got it from his communist buddies in Hanoi they probably would not have deactivated the automatic fire. If he got it from them, and he probably did, I would bet it's a fully operational piece.