Longer barrel = higher speed = more rpms = better terminal performance. Shorter barrel = lower speed = lower rpms = lesser terminal performance. The further he shoots, the more Sg he has, using the same load. So, yardage has a telling effect, even if the same load is used. One bullet will not do the job at all distances. That is why we need to know at what average distance he shoots and whether he is hunting or target/tactical shooting. A 300 Weatherby will not work up the speed to disintegrate a 150gr Accubond, even if the barrel is 28" and the twist is 1:9", it is a moot point.