Ejecter marks on .300 Wby cases.

[WyPL59]

I retired a W German Mk  V in .300 Wby. 84.5 grains 7828SSC gave sub moa (.75”) groups with 3182 fps. Bought a new Mk V Backcountry, same load was leaving “Hammer, and ejector marks”in base of case, reduced load to 84 grn and got a .625 group with 3276 fps. Opened a new can of powder and loaded up 20 rounds, grouping went down the toilet and started showing over pressure symptoms again,  chrono said 3382. I am currently down to 82 grns and 3278 fps with 1” group, no hammer marks on base but still getting ejector marks. This rifle had a very stiff bolt throw out of the box, I spent hours cycling it for break in Are ejector marks common and maybe I’m just noticing them now that they’re on my radar?

[224KING]

Sounds like your new Mark V has a tight chamber.As outside temps rise you may have to back off some more if you plan to shoot a lot this Summer.