Belgian likely finished in Germany.
The max. load was only marked 1897 - 1903
2.39 gram powder = about 36 grains of "Schultze" which was a 42 grain = 3 Dram bulk smokeless powder SO that would be the standard 2 1/2 Dram load with 28 gm = 1 oz. shot
The L bore and muzzle dimensions in mm are marked. R only bore so the choke is less than .008".
The initials are likely the barrel maker but could be the gun maker. ?something J? Are there no initials on the action flats?
Likely 2 1/2" chambers.
Looks like a nice 3 Iron
Damas Crolle with remarkable contrast for a 125 y/o gun.
Cocking indicators with a replacement screw in the top lever.