I purchased a Ruger 308 that apparently has a tight barrel (.300" bore) that will allow only minimum starting loads. So far I have tried IMR4895/H4895, IMR4064, and Winchester 748, anything more than the minimum charge and primers are flattened. I am using matched + or - .4grn R-P cases with CCI & Win LR primers, the barrel has a long throat that will allow up to 2.850" as a max loaded cartridge length and still have a .025 jump before engaging the lands. I encountered a similar problem with a 243Win 25-30 years ago that would only allow minimum/starting loads too. I thought stick powder being bulkier than ball powder might be contributing to the problem, I have Winchester 748 on hand that I tried which flattened primers too. I am using Nosler 150 & 165 grn Solid base bullets that have a fairly long bearing surface approx .330" for both bullets. 150 grn Factory Remington and Federal ammunition seem to produce normal velocity (2800 FPS) out of a 22" barrel with normal rounded primer indications!! Both brands of ammunition have approx .250" bearing surface on their 150 grn bullets, could .080 less bearing surface and softer copper jackets produce this sort of anomaly?? William
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