There has only been 1 crime that has ever been committed with a class 3 weapon  (full auto, silencer/suppressor, SBR, etc.).  Guess who committed that crime?  It was a cop! Not a civilian. What a shame ... but it's true. Many, if not most, people do not have the slightest clue what a person has to go through in order to LEGALLY own a Class 3 weapon. They have to go through a local background check, a state check (professional photo and police figerprints), and finally an FBI check. Months later you're given approval (roughly 6 months or longer).
The fact is that there is NO justification for these gun laws, these ridiculous bans, or the mentality that GUNS are bad. 
Some people have this misconception that "high caliber weapons" and full auto are at all in the same classification ... they are NOT. You can buy a high power rifle at most ANY sporting goods store. 
Reread what the 2nd amendment of OUR Constitution states. Read the Constitution. States have the right to govern themselves however they see fit ... as long as the Federal government doesn't have a law regarding that specific matter.