To those of you who have commented, why not say why you shoot to stop, rather than making some backhanded attempt to slap the notion that someone would want to discuss the subject?
Aim for center mass. Where you hit is another matter altogether different b/c you cannot control what the other guy is going to do. You may fire five shots are the center mass and not hit once, and you may fire one shot and go straight through the heart. Either way, the objective should be to stop the threat regardless of whether or not it kills them.I always taught to hit center mass and that was the beginning and end of the training.