Still puzzling over the higher than expected velocity, I checked the diameter of these SPS partitions. It seems fine at .2568". I tried slipping one into a fired case mouth and it took a pretty good bit of force. So I checked the diameter of the Barnes 100 TSXs that I've been using since I first got this rifle 15-20 years ago, and they are .2565" - not really enough to matter I'm thinking, but I could be wrong. From checking case mouth variance, I already knew my case mouth walls run .014-.015", which is a little on the thick side, so I think I will give them a light turning and see if that gives a little smoother slip fit of a bullet into the fired case after the next rip to the range. Perhaps the neck is being pinched a bit in the chamber.
BTW, I deprimed with a Lee universal deprime die, sized the cases using an RCBS FL die with the decapping/expanding rod removed, then expanded the necks with a Sinclair expander mandrel, which put them only .002-.003" under bullet diameter prior to seating the bullet, if that makes any difference.
Happy shooting,
Rex
