My factory ammo is from lot number 315***** could you measure your brass and see what it measures? I found a chamber print online that seemed to say right in front of the rim should be .299. My fired brass is .298.
Just measured a case from lot 3152818, once fired factory load: it measure just under .296 just ahead of the groove.
Just took this picture of the case:
Apologies to the OP for highjacking the thread




















































