How many cases are there, really, where an armed citizen has saved himself or others by whipping out a pistol? I've read of such cases in the news (it seems usually to be a granny for some reason), but they seem to be very, very rare. And newsworthy.

I'm not talking about scaring off a home invader at midnight. I'm talking about people packing guns in public and using them to fend off or to shoot actual criminals.

Obviously it happens, but how frequently in comparison to the 10,000 gun killings per year?