The Soviet M1940 Mortar

By Stephen Stuart

World War I saw the advent and proliferation of in all practical terms modern mortars. During the lull between the First and Second World Wars, the Soviet military had begun research and development of a variety of small bore mortars. The first small bore (5cm or 50mm for Soviet development) mortar to be accepted and issued was the Model 1938, in the year 1938. This mortar was subsequently taken out of service and replaced by the Model 1939. No sooner had the M1939 been fielded when it to was deemed unacceptable and was replaced by the more simple Model 1940.

Mortars are indirect fire area weapons. They are to be used in defilade fire against targets (by employing defilade fire, the chance of the enemy targets engaging the mortar emplacement with direct fire weapons is greatly reduced). Most mortar missions’ (or fire missions) are the result of either a forward observer spotting targets of opportunity and reporting the location to the mortar team or the mortar team itself spotting a target for a fire mission. If a forward observer is the one that spotted the target, the observer is responsible for adjusting fire on the target area.

The Model 1940 mortar is a pretty simple straight forward conventional design. It has a barrel, baseplate, bipod legs, and a simple sight system. The barrel was a smooth bore design and is 21.0 inches in length. The barrel cap in the base contains a fixed fire pin. There is no trip or trigger mechanism for firing the mortar shells, it is strictly a muzzle loaded dropped fire system. The bipods are made out of pressed steel and can be easily folded together then back against the tube for transport. The legs can be secured in the open position by a small metal ring or it can be pushed over the lip of the legs when in the open position. The bipod legs also have traverse and elevation gears which control the angle of the barrel during firing. The elevation gear allows the elevation to be set between 45 and 75 degrees. The traverse can be adjusted to 9 at 45 degrees and 16 at 75 degrees. Between the bipod legs and the barrel is a very unique device, a recoil buffer assembly. The recoil buffer system was used for taming the recoil of the mortar when being fired. This feature was discontinued in the Model 1941. To be honest for a weapon firing this small and light of a shell, there really is no use for this feature.

There are six vent holes at the base of the mortar tube. The range of the round being fires can be adjusted by simply opening or closing the vents at the bottom of the tube. To help the firer, there is a range a scale located on the base of the tube. Rotating the bakelite band to the right closing the vents for maximum range. Rotating the band to left opens the vents, decreasing the range. The minimum range of the Soviet M40 was 50 meters and the maximum was 800 meters. Rate of fire is listed in texts at thirty rounds per minute (the rate of fire is the maximum number of rounds per one minute of firing, the sustained rate of fire is 5 rounds per minute) personally I have never fired that many rounds out of my Soviet M40. The most I have ever fired in one minute was eight rounds. The mortar’s overall finish is a flat painted green.

The most common round available for the M1940 today is the standard High Explosive round (inert). The round weighs roughly 1.5 pounds and is in the standard configuration of most mortar rounds; tear shape. The shell is 8.25 inches in length. There are three sets of tail fin sections (each section contains two fins, for a total of six fins). The sections have been welded directly to the body of the mortar round.

Around the tail assembly are a total of ten exhaust holes, roughly 0.166 in size. The holes allow gas from the propellant to escape, launching the round from the barrel. The fuze assembly located in the top section of the round is a non-mechanical type (non-mechanical means there is no delay mechanism for the fuze) so the round was impact detonated.

The fuze assembly can be screwed from the body by rotating the assembly counter-clock wise. All the rounds in my collection and the ones I have seen in museums and at collector shows all have a bakelite ring that the fuze mechanism screws into. Then the bakelite ring screws directly into the body of the projectile. The price of rounds runs between twenty-five to a hundred dollars at this point in time. The price is based more on these rounds being antiques and collectibles of World War II, than on practice rounds for shooting purposes.

The Soviet M1940 mortar was used throughout the opening days of the war, consequently large numbers were captured by the German Forces. Germany soon started using Soviet M40’s in place of and with their own 50mm mortar the Granatwerfer 36. The Granatwerfer 36 was a short, very well built light mortar. However, the effective range of the Granatwerfer 36 was 500 meters maximum. Around 300 meters less effective range to the Soviet M40, this shortage in range in comparison to the Soviet model led to the use of the Soviet mortar when ammunition was in significant numbers. In 1941, the Soviet M40 was redesigned into the Model 1941. The Model 1941 was basically a Model 1940, but with the following changes: the baseplate was hinged to the barrel, and the recoil buffer mechanism located between the barrel and bipod was dispensed with. In the early parts of the war, a normal infantry division had roughly 84 50mm mortars. This would change as the war progressed, in the final years of the war the 50mm mortar was obsolete and almost completely replaced in the field with the larger M 41/43 82mm Mortar. The Soviet M41/43 in 82mm could fire a much larger shell (HE 7.4 pounds) at longer distances (3100 meters).

The Soviet M1940 mortar is considered a destructive device. This entails having to undergo the same process of buying any other National Firearm Act firearm, two sets of fingerprint cards, either a Form 4 or Form 1 ( a Form 1 if your activating a Dewat See details on Form 1 in SAR Vol. 1 No. 10 ), law enforcement signature, two passport photos, and of course the two hundred dollar transfer tax. The main problem with acquiring destructive devices is that if you order a destructive device from a dealer out of state, you must have a destructive device dealer in your state to transfer it to. This sounds easy enough, but the reality is there are not that many dealers out there that have a destructive device license. The reason is there are not too many people interested in buying destructive devices to make it lucrative for the dealer to pay the fee and acquire the license. If you have a Federal Firearms license you can do the paper work done up front (like a normal Form 4) and have the device shipped directly to you. If one has the Curio & Relics license, you can have devices listed as Curio & Relics on the register shipped directly to you as well on a tax paid Form 4.

This article first appeared in Small Arms Review V3N3 (December 1999)
and was posted online on October 23, 2015


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