Full auto guns are still legal, the law is just set up to make a class system. If you are wealthy you can have one. You can also have one if you are one of the governments special people. The so called ban only effects the lower class people. Dumb law anyway. A file is all the tools needed to make most simi-auto guns full auto. The law has yet to be challenged an most people I have talked to think it will die if it ever does.
As for background checks, I have not had to do one to buy a gun in 9 years. Besides, it is easier to buy a gun on the street than it is in the store an thats with me not having to do the background check. I like my guns to be new so I buy new. Most people I know don't cause its a hassle an it costs more. I have no reason to think criminals would go buy guns new if the checks were not there. An the few that try now are never charged.
By the way, supreme court has agreed to hear a case on gun rights for someone convicted of domestic violence in Tn. I expect the man to win.