What's so special about 100 yards? It seems a long way out to me. I would think a bear charging would be much closer.
Nothing really. I was just picking 100-yard as long-estimate. As I said, I don't think it's possible to argue self-defense at that distance, or anything further. 50-75 yards is probably a little more arguable, and anything less than 50 is probably likely. Bears can move at a pretty good clip. I would think a 200lb+ black bear could cover 75-yards in a hurry - much faster than a dog.