A Chinese copy of the Mauser C96 pistol manufactured by the arsenal of Shanxi warlord Yen Hsi-shan from 1929 to 1931.  It was unique in that it was chambered for the .45 ACP cartridge, rather than the 7.63mm Mauser or 9mm Parabellum chamberings typical of C96es and their many Chinese and Spanish clones.
shanxi type 17