Milsurps Knowledge Library - 1941 Swiss Model 1931 Short Rifle (K31)

1941 Swiss Model 1931 Short Rifle (K31)
(Manufactured by Eidgenoessische Waffenfabrik, Bern)

(Click PIC to Enlarge)

Caliber: ......................... 7.5x55 Swiss (GP11)
Rifling & Twist: ............... 4-groove, RH, concentric rifling, 1 in 10.63
Barrel Length: ................ 25.65 in. (652mm)
Overall Length: ...............43.6 in.(1107mm)
Weight: ......................... 8.85 lbs (4.02kg) empty
Magazine Capacity: ........ 6 round detachable box magazine
Sights: .......................... Tangent-leaf sight graduated to 1500m
Qty Mfg (Military): .......... 582,230 (1933-1958) Eidgenoessische Waffenfabrik, Bern
Qty Mfg (1941): .............. 54,150 Serial # 632576-686725
Bayonet: ........................ Models 1899/18, 1918, 1918/55 and 1914 Pioneer (Sawback)

Sources: ....................... Swiss Magazine Loading Rifles, 1869 to 1958
.................................... by Joe Poyer - ISBN: 1882391322
.................................... also selected content courtesy of Guisan and Copyright SwissRifles.com.

Canadian Collector Market Value Estimate: $

1941 Swiss Model 1931 Short Rifle

(94 picture virtual tour)

Observations: (Courtesy of Guisan - Copyright SwissRifles.com)

By the end of the 1920s the Swiss began to question whether or not they should equip their soldiers with rifles or carbines. Indeed, 2/5th of the Infantry and 3/5th of the rest of the army were already equipped with carbines rather than long rifles. While the rifles provide better accuracy and range, the carbines were lighter and easier to handle. Interestingly enough, while the carbines accuracy was considered adequate for military purposes, it was the member of the various private Swiss shooting clubs that were insisting the more accurate rifle be kept in service.

In 1928, first attempt at combining the positive qualities of the rifle and carbine was made by fitting a K11 with a heavy barrel. 200 heavy barreled carbines were produced and tested. However, the gains in accuracy were outweighed by the added cost of the weapon. The decision was made in April 1929 that a new design for the carbine.

The following requirements were set for the new weapon

1. The new weapon should not be significantly longer than the 1911 Carbine.
2. The new weapon should have a straight-pull action
3. The new weapon should be more accurate than the 1911 Carbine, and as accurate as the 1911 Rifle
4. The new weapon should be cheaper to produce than the 1911 series.

Testing began in late 1929 and continued into 1930 of two prototype designs, and end with favorable results. In late 1930 10 new design carbines were sent to the shooting school in Wallenstadt for evaluation. The new design carbine’s accuracy was compared with that of the 1911 Rifle and the heavy barreled carbine. The results of the testing showed the new design carbine to be more accurate than either the rifle or the heavy barrel carbine. However, there were some design issues that needed addressing.

In May 1931, a series of 200 improved carbines were produced. These carbines were issued to various shooting schools as well as six recruit schools. The testing continued until October 12, and produced the following conclusions:

1. The new bolt design was less prone to binding.
2. There were fewer feed problem.
3. The new action was less prone to failure, even in the event of one of the locking lugs breaking.
4. The new stronger action was better able to survive firing with a barrel blockage.
5. The new designs proved very durable, four carbines had 150,000 rounds fired through them without any appreciable failures.

Unlike the previous Schmidt-Rubin series of rifles, the new carbine’s locking lug locked up immediately behind the chamber. This afforded several advantages. The entire action was strengthened as the lugs were locking in a much thicker part of the action. Lock-up was also more precise. The bolt was significantly shortened, allowing for a longer barrel and sight radius, without increasing the overall length of the rifle, moving the rear sight closer to the eye, and cutting in half the amount of time for the firing pin to strike the cartridge after the trigger was pulled.

The new carbine also had several other new features. The barrel was intended to be free floating. The action itself only connected to the stock by two screws, one attaching to the chamber, with the second attaching to the tang. This allowed the Swiss to eliminate the aluminum barrel collar used in the Schmidt-Rubin series. The trigger was redesigned, as were the magazine and rear sight.

The end result of these modifications produced a rifle that was more accurate, yet cheaper than the K11, it was replacing. In 1932 it was estimated that the cost of a K11 would be 169 Swiss Francs. Conversely, the new carbine had an estimated cost of 151 Swiss Francs.

On March 17, 1932, the Swiss Upper Parliament accepted the new carbine into service and designated it the Model 1931.

During it’s production run there were several minor modifications made to the K31.

1934, the firing pin was made thinner.
1935, the receiver was hardened
1936, the magazine shell was hardened
1941, laminated stocks were tested, but rejected
1944, due to supply shortages, Chromium Molybdenum was use in place of Chromium Nickel Steel on various parts. This experiment proved unsuccessful.
1946, starting with serial number 868,901, beech rather than walnut was used for making the stocks.

The K31 stayed in front line service until 1958, when it was replaced by the Stgw57. K31s were still found with some Swiss Military units, well into the 1970s. The total production run was 528,230 carbines, beginning in 1933 and ceasing in 1958.

Collector's Comments and Feedback:

1. The rifle displayed in the picture virtual tour has "all matching" serial numbers, including the bayonet, scabbard and frog. Even the sling is manufactured and marked "E. Wirthlin, Mohlin 1941". (Feedback by "Badger")

1941 Swiss Model 1931 Short Rifle (K31)

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