Banning guns probably won't do much. Any psychopath who wants to shoot up a school, will probably be able to find a gun to do so. Better yet, it's not like the government has enough money or resources to recall every gun that would be capable of shooting shit up.
The us should really focus on the mentally unstable people, rather than guns. That would probably end up doing more in terms of school shootings and stuff.
inb4shitshow, these are my sheltered opinions, feel free to let me know where i'm wrong in this.