Carhub48,
Picking through the numbers and letters you cite, I suspect when Raimey is able to post the photos, we will find the drilling is chambered for 9.3x72R proofed for a copper jacketed bullet(K m G). A common marking for the bore( not groove or bullet) diameter for 9.3x72R rifles is 8,7mm ( Germans used a , where we would use a .). With markings like this, the drilling would have been proofed after 1911. Once Raimey has clear photos, either he or I or other members will be able to offer additional or better information.
Mike
