Vol423,
The rifle was proofed in Feb, 1907, at the Zella-Mehlis proof house under the log number 546( the five hundred forty sixth one in Feb. that year). The 108.49 is the bore( not groove or bullet) diameter, expressed in gauge measurement. This is one of three bore diameters often seen on 9.3 mm rifles of various nominal cartridges. Just from numbers made, the most likely cartridge is one of the 9.3x72Rs. A second choice would be 9.3x57R( 360- 2 1/4"). Rifles with this bore diameter often have a groove diameter of about .362".
Mike
