So apparently the tooling marks at right angles to the bore axis are broach teeth chatter marks as someone may have noted earlier or on another post.
8/23/21 update. I was fortunate to find a box of Hornady 300 gr XTP MAG bullets earlier in the summer. Had been loading 300gr XTP (not MAG) bullets with disappointing accuracy. Loaded a few rounds with 49 gr CFE BLK and same COAL and shot them today. Three shot1 1/4 inch group at 100yards!!!.
Three shot group is not definitive but this certainly is progress!
