Take a peak at the M1906-08 Mauser self-loading pistol
Chambered in 9x21mm, Mauser made less than 100 of these rather interesting guns (with the highest serialed at #77). This example is serial no. 51. These guns used a 20 round double stack detachable mag rather similar to their legacy C96 Broomhandles but operated through the use of a flat-locked action. Example has a 4-inch half round-half octagonal barrel and used a mix of rust and fire-bluing in its beautiful old-world finish. This particular specimen was in the Visser collection and then in the collection of Dr. Geoffrey Sturgess before being sold again at auction in 2014 with a value of $40-$50K via Julia Auction House
It appeared a century later in the game Iron Grip : Warlord