Incidentally, re the firearms displaying gold crowns on their exterior, (as opposed to crown proof/maker stamped marks inside the action), 7 pearls represents a baron, 9 pearls a count.

Re the "8.7" marked rifle, Baron von Engelhardt wrote:
8,7m/m on lower barrel: The very commonly used 9,3x72 (now called 9,3x72R) frequently was marked as 8,7 and similar.

As you know, there is a D and an E version of this 9,3x72R case, (if it actually proves to be that case). I have the D version of it and the CD4H FL dies and modified (rim thickness reduced), cases for it.