How does a law that prohibits a convicted armed robber from legally buying a machine gun fit into your view above?
Well, lets take a look at the most famous incident of machine guns used in a crime. That would be the North Hollywood shootout, carried out by Larry Phillips Jr and Emil Mătăsăreanu in 1997.
Now wait a darn second! Those two guys were not able to legally own a fully automatic weapon. Are you saying criminals didn't obey the law?
Shocking...
But thanks for proving my point. No matter how "tough" the gun control law (and there are none more restrictive than those related to fully automatic machine guns), it will not deter criminals from obtain that which you hope to ban. These laws therefore only put law abiding citizens (and in the case of North Hollywood, the police) at a disadvantage.
Now that's insane.