I am looking at building a fast-twist gun to shoot the 115 6mm bullet or the 133 .257. Both are the best B.C. hunting bullets I can find in those sizes. My needs are hunting based, and will be shot with suppressor on backpack hunts (so 7 1/2 lbs with scope). Target animals are antelope, mulies, blacktail, caribou, and Coues. I have elk guns already. The reason for the high BC bullets are the high and unpredictable winds. Hunting ranges 300-500 yards, although will practice shots out to 1000. Will be reloading. Soooo, what I was interested in was an options on maxing out the 6mm or .257 and which would be the better long range hunter. I keep going back and forth and not making progress. Of course after I choose the bullet, then the caliber discussion follows (6mm Creedmoor, 240 Weatherby, 25-06, 25 Creedmoor, .257 Weatherby etc...)