Could that mark be 2,5 GBP. This would be 2.5 grams (about 38grains) of "Gewehr Blättchenpulver" (Military Rifle Flake Powder). 7.7 would give a bore dia of .303" This may indicate a deep grooved bbl for a .318" 8mm bullet. Suggest a chamber cast & bore slugging to determine for sure. Certainly sounds within range for an 8x57JR, but not likely for an 8x57JRS.


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