This rifle was made on a slightly modified original Mauser, Oberndorf, commercial action pre-WW1. There ought to be Mauser serial numbers on underside of the receiver, behind the recoil lug, and on the rear wall of the magazine box. These numbers allow closer dating of the action.
It was originally proofed post 1911 by the Suhl proofhouse for the then 8x57I load with the 14.7 g = 227 gr steel jacket bullet load with 2.67 g Gewehr – Blättchen – Pulver = 41 gr (smokeless military) rifle flake powder.
After stocks of 8x57I ammo dried up after making it was prohibited by the Versailles so-called "peace treaty", it was rechambered to the civilian 8x60 and duly reproofed in Suhl April 1933 for the 12 g = 185 gr bullet 8x60 load.