Re: 300 RUM Primer question
My sendero in 300rum does that also, and does not matter how hot or mild the loads are. I use 96 grns of retumbo behind the 208 A-max and the 210 berger. The primers are flattened just to the edges but still have rounded corners but even with the load I started with at 92 grns the primer still flowed back into the firing pin hole. The hole is too large for the pin diameter. Just some of remingtons quality control downgrade.