Don't how "extreme" the shot was on the caribou, but it was with an early .41 Magnum. As I recall the range was maybe 150 yards--thought that's still pretty long with a sixgun.

I believe the story is in HELL, I WAS THERE! Might check and see if I can find it.

“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.”
John Steinbeck