Shooting someone for throwing a punch will make your defense attorney richer. Do you remember the reason for a concealed carry permit? It's not to protect other people or society. It's so that you can protect yourself and your family from the threat of death or grievous injury, not so that you can play hero and stop crime. Leave that sort of thing to the professionals. They get paid for it, and their organizations have much deeper pockets than a private individual. Myself, if I'm in a bank thats being robbed, I intend to do nothing other than be a good witness unless absolutely necessary to protect myself and my own family.