I have noticed that almost everyone's custom builds are utilizing 26" - 30" barrels. I don't understand the logic. 99% of the calibers that these customs are built around are short action calibers and don't use powders that burn slow enough to fully realize the advantage of such a long barrel. Something else that I think about is barrel whip (oscillation). The longer the barrel is the more it is going to oscillate during the shot cycle, unless of course it is of very large diameter, in which case creating excessive weight. My "old" school of thought dictates that any caliber up to the 30-06 case family will thrive very well in barrels between 20" - 22" and magnums (i.e. .300 WM, etc.) do their best work out of barrels in the neighborhood of 24".