The rim of brass is thick to absorb the pressure because it's not supported.If the gap between the barrel and bolt face is over 5 thousands for a bench gun .I would move the tenon forward to get the barrel face closer to the bolt.Then reset the head space by turning the reamer the required amount.
I have seen one that was set up for a coned faced that had 20 thousands un supported and it ringed the brass with a mild load .Have you inserted the brass that you said had fingernail lines in them?
If the .135 is the total subtract the measurement from the bolt rim to the bolt face and see what you got .That will give your clearance .
I have seen one that was set up for a coned faced that had 20 thousands un supported and it ringed the brass with a mild load .Have you inserted the brass that you said had fingernail lines in them?
If the .135 is the total subtract the measurement from the bolt rim to the bolt face and see what you got .That will give your clearance .