For general hunting 100-300 yard shots with confidence that you could make a clean kill in most shot opportunities.
The question is what percentage of shots are you willing to not take -or- what percentage of shots are you willing to try despite a fairly high chance of a screw up and cripple? I have hunted with cartridges as small as the .257 Roberts recognizing that there would be shots I'd happily take with a .300 win mag that I was going to have to pass on with the Roberts. That puts the .257 into the stunt category, not because it won't work, but because it increases the chances of having tag soup at the end of the season if I restrict myself to "ethical" shots.
I think the yardstick you are describing is the .270 Win with 150 or 160 grain bonded or partition bullets or the 7mm-08 or 7x57 with 140 grain or heavier bonded or partition bullets.
