10-4 on get some preparation. That really big Grizzly isn't going to hesitate in his charge, cut you any slack per your lack of preparation. BTW even the general rifle course at Gunsite is good preparation for any potentially lethal encounter (far better than none at all.)
The only survival episode I've heard of is an Aleutian woman who jammed her fist down a bear's throat, and pulling it back, left her wool mitten, choking the bear.