Probably just start with smart guns, make them with some new cool virtual scope or something to get every dirt bag to want to upgrade. Also supply some sort of jail breaking hack for them to try to feel secure with their new gun system. Make up an elaborate hoax about some evil Villain getting away with his jailbroken gun. Then just track the perpetrators and take um down one by one as they sigh up! That's how I would solve the gun problem, would take decades of planning and stages though! lol