My favorite hunting rifles for small to medium game are my 6 creedmoors with 105gr Berger Hunting VLD's.
But when asked by friends what to build/buy, between the 6 and 6.5 creeds, I always ask, "are you going to hunt elk with the rifle". If answer is "yes" my answer is 6.5 creedmoor. The 140 class bullets with the 6.5 creedmoor simply provide's more energy than a 105 6 creedmoor.
With that said, I'm fully confident in my ability to place a shot perfectly, and the effectiveness of the 105 Berger, to take a shot at a cow elk to 300 yards.