It is a lovely fantasy, and certainly a humane one, to think of picking your target with such precision and thinking that you would calmly track to just that region where you won’t make a fatal wound. I have never been in the situation, and hope never to be, but folks who say many things that sound sensible to me suggest that the single priority in a confronting-the-shooter situation is to stop that shooter. Your fine motor skills will be out the window. It will take all the training and practice you have put into it to rely on and you will be fighting an adrenaline rush that none of us can imagine, I gather.
The humane impulse is certainly laudable, but study up and think very seriously about whether you can accomplish that or will just jeopardize yourself by striving for a very difficult goal, as well as jeopardizing everyone around you if you do not succeed and are put out of action yourself.