I was charged by a big brown bear once. It let out one hell of a growl, poped it's jaws, and here it came! In the big woods, it echoed quite loudly. I would have had plenty of time for two shots with a bolt gun.
I chose to put the cross hairs on it's head and let it come in. I wanted it under 20 yards for a sure kill with the first shot, but at about 25 yards it saved it's own life and broke off the charge!!!
When it stopped, it walked back and forth popping it's jaws, and woofing. When it was side ways to me, i moved the cross hairs to the top of it's shoulders, but after a time of walking back and forth, it moved off "slowly". I stood there for a time to make sure it was gone, and then went back to hunting.
Drilling Man