In Lowell, MA there was a terrible shooting on New Year's Eve. Since criminals just won't obey the rules, I think we need to ask who was the last legal owner of the gun. That's the place where it goes wrong.
I suggest a three-pronged attack. 1. full licensing and registration and strict controls on new gun purchases. That would eliminate straw purchasing. And 2. background checks on every transfer. That would eliminate all those supposedly inadvertent private gun sales to criminals. And 3. enhanced and strictly enforced safe storage laws. This would cut down on theft.