I purchased this rifle used about a month ago and on the 3rd reload on new Remington cases I had a case separation. Was using 55 g of IMR 4831 and 100 g bullets which I had worked up to with no pressure signs. (been loading this caliber since 1972 with no events) I thought. After this I inspected all the cases and found that white ring on the very first ones. However some WW 270 cases Did the same work with no problems. Actually with H4831. Epps says Remington cases won't last any longer but the first firing (no sizing) produces the ring. The Ruger has very slight movement in the breach block when locked up. So do I send the rifle back or try different cases. Appreciate any comebacks except the ones that say there is more to the story.