[lugerholsterrepair]

If these are where I think you say they are, I can see no reason for them. The Crown M is an Imperial Navy acceptance mark. Not really meant to be hidden like this? But one never says never when it comes to Luger's.

The real reason to see these markings clearly is to determine their probable authenticity. Crown M Imperial Navy acceptance marks are often faked. But if I were wanting to fake some I would make them larger and put them where the average buyer would see them easily. Not on the breech face X2? Likely some of the Crown M Imperial Navy acceptance mark experts can tell us something about the breech face placement? Since we will likely never see the marks with any clarity.