Adam,
You would really be surprised at how many full auto firearms there are out there that are unregistered. I personally know of at least 10 full auto arms that were brought back as Vietnam war trophies that were not "fixed". Guess what! Not even one has been used in the commission of a crime. A couple are fired fairly regularly. I also had a fellow back east that wanted to sell me his little British Sten gun. Even though it was a 9MM he thought it was too expensive to shoot. He told me he didn't have too much luck with reloads and the factory 9MM was 6 bucks a box. Course a box lasted a whole 30 or 40 seconds...counting putting in a second mag. He said he was retired and that was a whole lot more than he made for 30-40 seconds of retirement pay.
I have been lucky to have known quite a few people that had full auto arms and got to try 'em out. What a hoot!
I also knew a fellow who had a Browning 1919 light machine gun that his grandfather bought...way back yonder...but never got to shoot it...darn it. But we did get to dispose of 2 cases of hand grenades though. They were really old and every one went off.