BAN ALL FIREARMS ACROSS THE USA.

I come from a developed country in Europe and our constiution is slightly more modern despite the fact that the country is a few thousand years old.
I think there is no reason to maintain the right to carry weapons since the times of the WILD WEST are over.
In Asia you do not witness such killings.
More weapons will just worsen the siituation.
As you can see in the developed world, there are almost no killing sprees which are sadly almost "normal" in a country which claims to be free.
Declare all firearms illegal (if not used for hunting or sports) and ask the owner to return it within a certain period of time. Everybody who does not comply may face severe penalties.
Provide better education, less crime on TV and video games.
Intelligent people do not need weapons to discuss differences