I'm reloading the same PRVI brass (7 x so far) and have never had the problem. It makes me wonder about an headspace origin ; if it was me, I'd try partial sizing to conform to the individual rifle's chamber. BTW, are you sure you're using a FL sizer made for the K31icon (some are made for the smaller 1911 chamber). My Hornady dies came with a smaller "1911" sizer which made it very hard to resize brass coming out of my larger K31 sizer. I solved the problem by ordering a separate K31 FL die from Redding (BTW, Redding 7.5x55 dies are made to K 31 dimensions).