I find it odd that anyone would find the alternative calibers listed in the original posting, to be a bit less capable that a 270, at 400+ yards.
I will add that I'm a dedicated 270 guy.
Take a look at what the lads did in the old Schutzenfest days. It's the skill of the man, not the rifle, as you range out. And those old guys were shooting offhand. With blackpowder. Without scopes.

Imagine your grave on a windy winter night. You've been dead for 70 years.
It's been 50 since a visitor last paused at your tombstone.....
Now explain why you're in a pissy mood today.