Drillingis a word derived from the German word for 3, so as I understand your post the 9x57R would be a double rifle, not a drilling. I am only getting one picture, the underneath of the chamber area for the drilling. The 6.3/70 would be bore size not including rifling grooves with a 70 mm long chamber. The 3.25 means it was proofed in March (3rd month) of 1925. It was the 270th gun proofed that month. While not visible in this picture from 1925 it should most definitely carry a smokeless powder proof.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra