You missed the point, a few pages ago I linked an article showing a country where guns are severely restricted (I'm being generous) and they are looking into banning knives, now its acid. In effect, I'm saying banning anything will not stop this behavior. I think your point is the gun makes the attack more massive, and while correct, Timothy McVeigh, any 9/11 attacker and so on might disagree with you. I'd argue cars are more dangerous.
And a seriously restrictive gun law will not be passed, at least in the next few decades, not even worth arguing about.