The Karabiner Modell 1931, designated K31, is a straight pull bolt action carbine manufactured by Waffenfabrik Bern (W+F Bern) in Bern, Switzerland. The K31 replaced the earlier Model 1911 carbine and served as the standard issue infantry arm of the Swiss military from 1933 through the 1960s. The straight pull action allows the bolt to be cycled with a single rearward pull and forward push of the bolt handle, without rotation by the shooter. The bolt assembly uses a sleeve with two locking lugs that rotate into the receiver via helical cam tracks as the bolt handle is pushed forward, locking the action. The K31 is chambered in 7.5x55 Swiss (GP11) and feeds from a detachable six round box magazine that can also be loaded from the top via stripper clips. The barrel is 25.7 inches in length. Sights consist of a blade front sight with protective ears and a tangent rear sight graduated from 100 to 1500 meters. The stock is two piece walnut with a pistol grip, full length handguard, and a steel buttplate. A sling bar is fitted on the left side of the stock.

This example bears serial number 225270, which falls within the 222451 to 239600 serial range produced in 1954, among the final years of regular K31 manufacture. It is also within the broader 215001 to 350000 serial block for K31 carbines ordered by the Kriegstechnische Abteilung (KTA) for the Kriegsmaterialverwaltung (KMV). The receiver, bolt, and magazine are serial number matching. The receiver is stamped with the Swiss national crest, and the right side of the buttstock carries the Swiss cross in shield cartouche. The underside of the barrel is import marked towards the muzzle. No additional accessories included.

Specifications

• Manufacturer: Waffenfabrik Bern (W+F Bern)
• Model: Karabiner Modell 1931 (K31)
• Caliber: 7.5x55 Swiss
• Serial Number: 225270
• Date of Manufacture: 1954
• Action: Straight pull bolt action
• Barrel: 25.7 inches
• Receiver: Steel
• Finish: Blued
• Stock: Two piece walnut, pistol grip, full length handguard, steel buttplate
• Sights: Blade front with protective ears, tangent rear graduated to 1500 meters
• Magazine: Detachable 6-round box magazine