WOW, an other thread gone a stray!!! I have had/do 243 Win, 300Win Mag, 30-06, 270Win, 257 Roberts, 257AI, 257WM, 45-70 for hunting deer, lopes, elk and black bear, my son's use 257AI's for all that too, that is there only center fire rifles, and for hunting those animals use 115NP only. All have dropped them DRT or they went only about 30 yards, (elk and Bb). I have killed deer and lopes with the 243, 270, 257AI, 45-70, I have killed elk and BB with the 300Win Mag, and 270Win, BB with the 45-70. I just got the 257WM and have not used it yet. All kills were DRT or went just a few yards till the lungs bled out. In the lighter calibers I use Nosler PT's in the 270, and the 30's Sierra PntBT, and in the 45-70 all and anything kills!!
Now I am down to just a 257WM and a 45-70 for game. My point is all a certain cartridge gives you is different span of bullet wieghts and velocity. Yes the 270 could be the one gun, varmits to big bears, but I would rather use a 243/257 for varmiints and have better BC and SD for the same weight bullet then 270. 7mm, or 30 cal. Same thing as the game just got bigger, a larger caliber, a deer and lope have such a sensitive nerves system that anything will kill them, now when you get to elk and bb, it gets different, so a larger bullet is in order but not needed under the right conditions/50 yard shot.
All a Mag gives you is longer killing range and flatter trajectory over a non magnum cartridge. For most non magnums they are good out to 300 yards in there game class. How many here can say they can hit a 9" paper plate at 300 yards in field conditions?? Usually off hand or prone with a make shift rest or bipod. I sure would struggle with it. So I think the last page and half has been egos arguing here and not looking at reality in the field or answering the OP. I paid 349.95 in Nov Cabellas door buster for my 257WM Vanguard, they flooded the market with them cheap, I was on a tight budget, could not pass it up, anything else would have cost me 200-300.00 more no matter what the caliber.