Here is your legacy. Very rarely do politicians have the opportunity you have right now. Call together lawyers and gun control advocates to the White House. Craft as restricting a gun control bill as possible that will not get automatically thrown out of court - definitely re-instating the assault weapons ban and making it a federal crime to carry a concealed weapon. Wait until the new Congress is in session. As soon as they establish their rules of order and hopefully create a talking fillibuster,have a senator introduce the bill as first order of business. Out of habit the Republicans will fillibuster it but after a half day of protecting assault weapons on C-Span they will give up (this is what the talking fillibuster is for Kevin Drum). Have the Senate push the gun bill through as quickly as possible and send it over to the House. The Republicans in the House will try and quash it. Take it to the people immediately. Make it your priority even more than the economy (dead children are a more immediate problem than tax cuts - I'm sorry).
Do not listen to any of your advisers!!! Do not listen to the media!!! Don't listen to anybody but your heart and what you feel when you look at your children. The people are with you in a way that is very rare. Strike quickly and be decisive. Do not compromise (maybe the next massacre will only have five dead children instead of twenty). There are three seconds on the clock and the ball is in your hands. Take it to the House Mr. President!!!!! (Of course in multiple ways).