This Chinese production C96 Broomhandle pistol is found in the collection of the UK's Royal Armouries. Curator Jonathan Ferguson showed it off recently in this video briefly.
It notably the word pistol engraved on the side where it should say Mauser. Just in case you couldn't tell I suppose.
It was a Chinese Mauser in the game but this particular one is a different small product knock off. For a period China had a number of warring factions that produced unlicenced pistol designs. IMFDB has it as a Type 17 in game. The one above has different markings and a full auto switch.
The creator of this sub's namesake Ian McCollum, of Forgotten Weapons, published a great coffee table book "Pistols of the Warlords" for anyone scrolling past us in All.