IMO Never pull a gun unless you intent to use it. just MO
But if I pull my handgun, with full intent to use it, and the threat turns and runs, I'm not going to shoot him in the back.
And now he can go and call the cops and claim that he was going to ask to borrow my cellphone when I drew my pistol and pointed it at him.
My word against his.
I would have to take my chances in court if charged.
But suppose I waited to draw...waited till he was slamming the hood...waited till he was elbowing the window trying to break it....waited till he drew a pistol of his own???
That's definitely NOT the answer.
Neither is drawing a pistol with an empty chamber.