I have a question for all the smiths out there. I have a 1903a3 that I shoot 165 BT's over 57.5g H4350. All cases were full length sized @ each loading (I just got in a neck die for the 06). Some of the cases are Winchester and some are R-P's. The Winchester brass is separating at the head on the 3 or 4th firing. Also when comparing once fired rem brass out of of my gun to once fired rem brass out of a rem rifle my brass is about .03 larger at the case/head junction (where the seperation is occuring). Also there are striations that circumvent my brass which are much more pronounced out of my gun than the Rem. So is the .03 a significant difference in chamber diameter? Is the rougher chamber causing the seperation? Is it simply a difference in brass? O.K. thats more than one question but any explanations or opinions would be greatly appreciated.