Hey Ardent,
this cut and paste from 6mmbr.com
Which is Better, Button Rifling or Cut Rifling? There is no clearly superior form of rifling. Check the results from major benchrest matches and you will see both cut-rifled Kriegers, and button-rifled Harts, Liljas, and Shilens among the trophy-winners. David Tubb has dominated cross-course and high-power shooting with Schneider pull-buttoned barrels, but Kriegers are favored by many Palma shooters and members of the USA F-class team. Button rifling can produce a very smooth interior finish, and the majority of winning 6PPC barrels are buttoned. On the other hand, many shooters believe cut-rifled barrels last a bit longer. By the nature of the manufacturing process, cut-rifling puts fewer stresses in the steel and twist rate is more likely to be uniform. Additionally, a cut-rifled barrel can be fluted before the bore is rifled. On buttoned barrels, fluting must be done after the bore is rifled and stress-relieved, so there's a chance stresses from profiling/fluting can alter the bore. The only possible issues we've heard with cut-rifled barrels, particularly Kriegers, is that the high, sharp lands can be tough on 6.5mm J4 jacketed bullets, such as the Clinch Rivers and JLKs, when they are driven above 2950fps in an 8-twist barre