K31

The Karabiner Modell 1931 (officially abbreviated to Kar. 31/Mq. 31; commonly known in civilian circles as the K31) is a magazine-fed, straight-pull bolt-action rifle. It was the standard issue rifle of the Swiss armed forces from 1933 until 1958 though examples remained in service into the 1970s. It has a 6-round removable magazine, and is chambered for the 7.5×55mm Swiss Gewehrpatrone 1911 or GP 11, a cartridge with ballistic qualities similar to the 7.62×51mm NATO/.308 Winchester cartridge. Each rifle included a 6-round detachable box magazine with matching stamped serial number. A stripper clip can be used to load the magazine from the top of the receiver.

The Karabiner Modell 1931 replaced both the Model 1911 rifle and carbine and was gradually replaced by the Stgw 57 from 1958 onwards.

Although the Kar. 31/K. 31 is a straight-pull carbine broadly based on previous Swiss "Schmidt–Rubin" service rifles and carbines, the Kar. 31/K. 31 was not designed by Colonel Rudolf Schmidt (1832–1898) as he was not alive in 1931 to do so. Mechanical engineer Eduard Rubin (1846–1920) was the designer of the 7.5×55mm Swiss ammunition previous Swiss service rifles and the Kar. 31/K. 31 are chambered for. The Karabiner Modell 31 was a new design by the Eidgenössische Waffenfabrik in Bern, Switzerland under Colonel Adolf Furrer (1873–1958). The first 200 Kar. 31/K. 31s were made in May 1931 for troop trials (serials 500,001 – 500,200), thus the model number of 1931.