you guys that say you would do nothing are.... well cowards. And part of what is wrong with america these days. There is NO WAY you can "tell" if the situation is going to escalate until he pulls that trigger.... the robber is in the driver seat. And that is NOT how this world is meant to run. But with all the liberal hippies and a couple of you guys sooooo worried about yourself and your "legal issues" you would rather wait till the very last second to decide if my wife/grandma/sister/mom/aunt/cousin/any female I know or care about is worth your legal battle.
Those are pretty bold accusations to be throwing at people you don't know after readed a few lines on a web site. I'm a hard core conservative not a liberal hippie. I will freely admit I've never been in this situation so maybe I would react as a coward, but I don't so.
No matter if you shoot or don't shoot there is a chance the clerk and you will die either way. Trying to figure out which one has the best chance of clerk/you staying alive is the goal. Therefore I (maybe I'm a dreamer) would like to think that some of the people saying don't shoot aren't cowards. They simple think that has the best chance to achieve the goal.
Along that line, is it more commen for muscles to clentch up (thus bad guy pulling trigger killing clerk) or to relax (drops gun) when someone experiences a gun shot wound?
Personally I agree with some previous posts. Move to get the clerk out of the line of fire (and get cover if possible) and shoot till the threat is eliminated.