I had a friend offer to GIVE me one of the .22s. Problem was, the previous owner had cut the barrel down (read: made it an SBR without bothering the ATF). But then it wasn't cycling properly, so he cut the recoil spring down. I watched my friend mess around with it for about a half hour, trying to get it to fire twice consecutively: no dice. He offered it to me: I declined, and pointed out the legal problems...
Last I heard, it was buried somewhere, until he can get a new spring and barrel...