Replaced Bolt sleeves on Model 1931 carbine (Created: 20.12.2018, Changed: 11.10.2023)
(Translated from German using Google Translator)
During Second World War, much was uncertain in Switzerland. Nobody knew if Nazi Germany would attack Switzerland and nobody knew how long the war would last all around.
Switzerland needed weapons, but had only limited resources. For example, there have been various material trial on different weapons to test more readily available materials.
Normally, the bolt parts of the
Modell 1931 Carbine were made from chrome-nickel steel (marked CN). However, in the war years of 1943, 1944 and 1945, due to material shortage some series of these parts were produced of chromium-molybdenum steel (mark Mo). For the bolt locking sleeve (part number
T-K31-42), which locks the bolt with the locking lugs, this material has proved to be less stable and there may have been hairline cracks on the locking lugs. In some cases even locking lugs are broken off.
The breaking of locking lugs, however, may not always be due to bad material: also shooting with an incompletely closed bolt (incompletely closed bolt:
Picture, completely closed bolt:
Picture) can cause damage, regardless of whether the sleeve is made of Mo or CN steel.
Well, the Swiss Army has identified the problem with the chromium-molybdenum-steel (Mo) bolt locking sleeves and began to replace them during inspections or in the Army repetition courses. For this purpose, unnumbered bolt locking sleeves were used. Since these sleeves were already hardened in the factory, no number could be stroken into the material. So the replacement sleeves were numbered using an electric pen, with the same number like the rifle.
Modell 1931 Carbine produced during the war years (1943 and 1944, but some in 1945 too) are therefore original, if they have an electro-pencil-numbered bolt locking sleeve. Weapons, which still have the originally numbered chromium molybdenum (MO) bolt sleeve, are of course very interesting from a collector's point of view. When shooting these rifles, the locking lugs must be inspected more often. Alternatively the bolt locking sleeve may be temporarily exchanged against a CN sleeve for shooting.
Bolt caps (part number
T-K31-37) and other parts of the K31 (like receiver) made of Mo-steel are absolutely unproblematic, as they are not exposed to heavy loads during firing.
For safety: in general, all weapons (I mean ALL) that are shot, should be regularly inspected for their functionality. Weapons with the MO locking sleeves should be examined at shorter intervals.
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| Modell 1931 Carbine, rifle serial 814530, manufactured 1944, bolt locking sleeve replaced and numbered using an electro-pencil | Modell 1931 Carbine, bolt locking sleeve, chromium molybdenum steel (Mo) | Modell 1931 Carbine, bolt cap, chromium molybdenum steel (Mo) | Modell 1931 Carbine, bolt locking sleeve, chrome-nickel steel (CN) | Modell 1931 Carbine, bolt cap, chrome-nickel steel (CN) |
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| Modell 1931 Carbine, bolt locking sleeve, chromium molybdenum steel (Mo) | Modell 1931 Carbine, rifle serial 785759, bolt locking sleeve, chrome-nickel steel (CN), locking lug broken | Modell 1931 Carbine, rifle serial 785759, bolt locking sleeve, chrome-nickel steel (CN), locking lug broken | Modell 1931 Carbine, rifle serial 785759, bolt locking sleeve, chrome-nickel steel (CN), locking lug broken | Modell 1931 Carbine, rifle serial 785759, bolt locking sleeve, chrome-nickel steel (CN), locking lug broken |
