But as Finland showed. Once guns have been made illegal, it takes almost 50 years before we see the full effect. People as a rule don't hand in their guns, and we have to patiently wait for them to break. Just looking at a couple of years right after a gun banning just doesn't make any sense.
Austria's extremely liberal gun laws and very low occurrence of gun crime leads us to believe that it's a complicated issue. We can't just point to the guns alone and say, without them problem solved. Post war Finland also had extreme low levels of gun crime even though every home had at least a rifle.
We can debate why the number of gun related murders in specifically USA and not Austria is out of proportion. It seems to be obvious that it's out of control in USA. The reason why USA as a culture can't handle liberal gun laws, and how it can be solved without removing them is another debate all together.
edit: We know they can't handle gun laws as they have it now simply by reading statistics.