Since everyone has a theory on guns, I will throw my two cents in.
I know something about guns. In the service I was the only one in my platoon who was rated expert with both a rifle and pistol.
First suggestion: All guns except those for law enforcement should be limited to three rounds. If you are a hunter and cannot hit your prey with three rounds, you are wasting your time.
Second suggestion: All manufactured guns should have a combination on them. The only one given that combination should be the buyer, who should be held responsible for that combination.