Bob,

I had a similar situation about ten years ago. 550 yards nice bull across a deep ravine. Wind blowing like hell. I saw a nice round rock about a 100 yards to the right of the Bull and held right on it. I hit about 4 feet to the right went back to the elk held off and fired. He fell over right there and stayed down. 2 1/2 hours later I got to the elk. Broke his neck. If that shot had been 4 or 5 inches either way would have lost him.
Pretty reckless and lucky, and I more than likely won't do it again but it worked pretty good that time.
Oh the rifle was a .300 Ultra with a 200 gr. SBT.

Lefty