I'll stipulate your premise if you can find me one instance where a person who applied for a concealed carry permit, received one, was carrying legally, and then went nuts and killed a bunch of people in a crowded area.

The simple fact is that does not happen. What does happen is the psycho you're describing illegally carries a firearm to a crowded area, and unloads it indiscriminately. If someone who was trained and licenced to carry a firearm were there perhaps they would be able to kill the madman and cut his reign of terror short. In fact, I believe you can find instances where someone who was carrying legally has stopped someone trying to kill people.

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