There seems to be two sizes of cases and chambers out there these days. The original stw was built on a 8mmag case which is .002 larger than the 300 win mag family of cases just ahead of the belt. I think the brass suppliers just started cheating and the chamber reamer makers may have followed the brass. I should restate the 7stw was .002 larger not the 8mm. I still have some new brass from back in the 90's that you could never chamber in a .513 sized stw. Also a 7mm would always clean up when chambering to an stw. They apparently don't now and I have seen several smiths post not to do it without setting the barrel back. My gun is a Rem. custom shop early stw and the barrel is a remarked 7mm.
We were finally able to make it to the range last weekend. I am happy to report that 12 shots were fired without any sign of sticking brass. The minor polish job using Flitz did the job. None of the cases had any marks in front of the belt like they did in the pictures I posted earlier. I think there was a burr in the chamber where it transitioned from belt to case wall.