Hello, I am a firearms enthusiasts and recently fired a few full autos back in Scottsdale, AZ. Since then I have been reading up about all things Class III. A friend of mine was telling me that he purchased a Thompson Sub from a guy in California for 1000.00 The story is that the gun was/is a prop gun from a movie set. Well, interestingly enough the lower receiver has a full auto/single switch. He was able to give me a few serial numbers also 583990 on the bottom of the receiver by the trigger guard. ANYWAY, I told him what the gun could be worth if it was still functional (the lower receiver at least). Now, I am learning that if it is a bring back or in general a non registered subgun thats been floating around, it's basically impossible to register. Has anyone heard of a situation regarding a full auto prop gun. I haven't seen the firearm, I was going to try and research it without inspecting it because I don't want to take possession of it unless its legal. Can anyone shed some light on the serial or perhaps provide me with something to look for so I can tell if this lower receiver is functional? Any direction would be helpful. THANKS.