you practice at 750, and 600 gets to be a chip shot, have taken dozens at 500 to 800 yards, but this is whitetails,, but the kill zone on elk is larger. it ain't hard. put a good bullet with enough energy in the kill zone and stuff will die.
anything more than 9 or 10X on the top end is overkill. mine has a compact 3x9 on it, but its a woods whitetail rifle,, have other stuff for extended range.
a buddy wanted one to eat, another wanted a skull, and have too many on that piece of property, just regulating the population. Its a big sow, their small head does not make attractive mounts. sent a 340# male off to be made into a rug last year.
The 2nd pic was my view of the bear from 7:50 till 2:30 when it finally got up and walked to an opening, the 135 Berger classic hunter done an awesome job at 2755 fps from my 6.5 creed AR10, the shot was 388 yards. Had a 50 cent piece sized exit