Hey everyone, Thanks to all your excellent advice I have prepped 19 matched Win cases just now. These cases which previously had the shoulders bumped back, have now been trimmed to 2.005. That is 10/1000 under the book spec. Neck prep completed. All 19 cases now allow me to close the bolt and open and extract the Empty cases, easily . I find it interesting that the same cases , loaded 6 times, in the same manner , suddenly become completely unable to chamber or extract correctly . It went from easy to requiring a mallet be used to tap open the bolt. Final note. The cases that had bases that measured at or near the book speck of .470 were harder to open the bolt and extract the case. However , the prepped cases that measured .466 at the base, allowed for very easy opening of the Bolt and case Extraction. This could mean ( Maybe ) the shoulder bumping was not ever necessary, and the issue was FL sizing was really needed to correct base diameter. Thank you everyone. I'm going back down to load the cases now.