As was done to curtail smoking, levy a high tax on semiautomatic guns, "assault" type guns, high capacity clips, and most ammunition used with these weapons, and dedicate the revenue to mental health research and management (emphasis on violence prevention).
Why is this important?
TAX THE HELL OUT OF GUNS AND AMMO, AND DEDICATE THE REVENUE TO MENTAL HEALTH CARE AND RESEARCH!!! IT'S THE SAME THING WE DID WITH SMOKING!!!