The goal of gun control is not to actually control guns and make the world a safer place, but to control people. It is not as important for you can pass a criminal background check so much as it is that you feel obligated to ask the state for permission to buy a gun. Liberals know gun control laws will not stop criminals, but it will erode the sense of independence and self reliance of regular people until they feel that they can do nothing that does not meet government approval.