Explain to me how none of the legally owned guns have been used in the mass shootings you described. I'll wait right here.
Let's start with Columbine. Were the shooters the owners of the guns used at Columbine, or were the shooters already in violation of gun laws when they took someone else's guns to that school?
You see kid, a law will not stop someone who ignores laws.
Gun laws CANNOT stop these shootings.
Instead, those two kids needed to be identified early on as having emotional problems, and gotten the treatment they needed, with or without their consent.
That's what would have saved the kids at their school, AND the kids in Connecticut, yesterday.
Guns are not crazy shooters. PEOPLE are.