As an update, I pulled the bullets on all of the ammo using a RCBS press mounted collet puller.

I weighed ten charges. They ranged from 68-70 grains of powder. The charges were compressed and I had to loosen the powder with a phillips screwdriver.

I tried 65 grains, still marked the case head, primers pretty flat.

I tried 60 grains, better, but still not comfortable.

I tried 58 grains, still had very slight markings

I tried 56 grains, and thought it looked good. At this point I fired a couple Winchester factory loads for comparrison. They had slight marks on the case head too. I decided to load them at 57 grains.

I think these rounds were supposed to be loaded at 60 grains and instead were loaded at 70.

I also think the WSM's have a pretty high bolt thrust due to the larger diameter and high operating pressure. So maybe some case head markings are normal.

Anyway, I finally have some ammo I am comfortable shooting. It is pretty bizarre to find factory rounds with 10+ grains too much powder in them.