That seems rather odd to me? I say this because regardless of how hard I seat them, it leaves no marks on the primer.
So to me, it appears your priming stem isn't aligning with the primer, or the brass isn't aligning in the shell holder.
Something to check:
Check to make sure the shell holder doesn't have any derbies or build up in the grove that preventing the case head from completely sliding all the way in. I've had this happen, not only with priming, but when resizing and seating bullets. Shell holders must be free of anything that can cause a misalignment issue.
GS2
