I do not support gun confiscation or bans. There are no panaceas, but we can do things that, over time, will reduce the carnage.
1) ban the legal manufacture of assault weapons. Don't get bogged down in definition; use common sense. Over time, if people can't get their guns replaced or repaired, violence will drop. Or if they can't get ammo...which leads to #2.
2) guns don't kill people - bullets do. So attack ammunition. Tax the hell out of bullets; ban calibers and sizes most used in mass shootings; ban high-capacity magazines. Sure, some people will get around these things...but it will bring down the rate of violence.
3) encourage responsible gun ownership by increasing penalties. If your gun is used in a crime, for instance, it's your ass. Lots of times this would just involve enforcing the laws already on the books. We all should be for this.
And by the way, private gun ownership does not prevent tyranny. That's just nonsense. Lots of very healthy democracies are not bolstered by private firearms - in fact, all of them, besides us.