I gotta jump in here, even if it is to agree with what is being said.
First, if there is any way possible, wait for your animal to stop. You have to go with the percentages. Nobody is so good that they should take a running shot, if they don't have to do it.
If you have learned to read body language, and you decide he isn't going to stop on his own, give him an inducement.
Usually, a lip squeak is the first thing that you try, followed by a bark.
Hell, I have even tried a burgler alarm, a whistle, honk the horn, and surprisingly effective; just talk to him. But really, there are times when he won't cooperate....so, learn to shoot him while he is moving.
Here again, you need to learn WHEN to shoot a moving animal. Wiley mentioned that they get more difficult up close, and I myself, prefer to handle them at about fifty yards, if possible.
If he is just coasting along, it is sometimes to your advantage to let him see you move. Sort of herd him toward or away from something.
Whatever it takes. That's why I carry a shotgun and a rifle, when they come in pairs or get inside on you.
Can't get them all, but there are those animals that you need to kill, when you get the chance. No excuses. If you are dumping over half of what you see, you are doing fine.
Good hunting. LB