can anyone tell me about the different nodes in a barrel. i have a 26" varminter contour 1:9 twist 243 ai barrelwhen fire forming i get good groups, when loaded a grain or two more than the fire form load not so good of groups. i was wondering if faster could hit the next node or settle for slow. i was getting like 2980fps on ok formed groups, but i should be able to hit higher velosities with these bergers(95grn vld hunting)