Mauser C96 cone hammer carbine
Converted to carbine by Carl Loguch in Germany c. late 1890′s - serial number 12.
7,63x25mm Mauser ten-round internal box magazine, short recoil semi-automatic, fixed foregrip independent of the barrel, dovetailed removable stock, Karl Kahles 1,5x~3x scope.
Not to be confused with the M1917 trench carbine which was built as such and had a very different receiver.
Sauce : James D. Julia Inc