I am not the "expert" that some of you claim to be but Perrier is correct in one aspect. A clean shot is the goal.
You can bring down most anything with a great shot but most of us are not "top shots".
This old sporterized O3A3 (30-06) brought down a big horn at just over 300 yards and will do for most big game.
I have most of the calibers listed above but if I was limited to one and only one hunting rifle this Finnbear 270 would be it.
One quick note: why is it that every thread that Perrier chooses to grace, goes sideways within a few pages?