Purcell, it's a real bear. However, the size, story about it killing Fish and Game officier / hiker, etc. is not. It was also shot by a fellow in the U.S. Air Force, not as some have said a Game officier.
The "Snopes" link Charlie P included gives the real story.
I sure wouldn't want to have to face that critter down with any rifle, if it was headed in my direct for sure...