It was a great success for Finland that, back in the 1920s, the designer Aimo Lahti got carried away with the design of submachine guns. Over time, the designer managed to create a number of small arms samples. And his 1931 model Suomi submachine gun became a truly successful weapon, turning into a serious threat to the Red Army during the Winter War of 1939-1940. At the same time, an unprepared person can easily confuse a Finnish submachine gun with a drum magazine with a Soviet Shpagin submachine gun of 1941, so this weapon of the two warring countries turned out to be similar in appearance.
Aimo Lahti. The creator of the Finnish automatic weapons
The creator of the Finnish automatic weapons was self-taught and did not have a special education, so in this regard, Finland was very lucky. Aymo Lahti came from an ordinary peasant family. The future designer of small arms and major general of the Finnish army was born in the village of Vijala in 1896, today it is the territory of the small town of Akaa. Aymo Lahti was the eldest of five brothers. Perhaps that is why, after finishing the 6th grade of school, he went to work at a glass factory. So he could help his family.
It is believed that it was at this time that, having bought a rifle of the Berdan system with the money earned at the glass factory, the future designer became seriously interested in small arms. After serving in the army and shortly working on the railroad, Lahti became a gunsmith in the Finnish army. In 1922, he became thoroughly familiar with automatic weapons, having studied the German MP-18 submachine gun, which could hardly be attributed to successful models. Based on the experience gained, the self-taught designer designed his own Suomi M-22 submachine gun, which, after being fine-tuned in the 1920s, turned into the serial Suomi Konepistooli M / 31, or KP-31. It is noteworthy that the weapon received the name of the country, the self-name of Finland - Suomi.
In addition to submachine guns, Lahti created a successful modernization of the Mosin M-27 rifle, nicknamed "Spitz" due to the characteristic front sight guard. Also, Aimo Lahti created and achieved the launch into mass production of the M-26 light machine gun, for which there was also a drum magazine designed for 75 rounds. The designer also created the Finnish 20-mm anti-tank rifle Lahti L-39, which could effectively fight all types of Soviet light tanks. But still, the Suomi submachine gun remained the truly successful and massive weapon of the designer.
Until 1953, the total production of Suomi KP-31 submachine guns amounted to almost 80 thousand units, for small Finland this is a very large number. At the same time, the Finnish military and police received almost 57 thousand Suomi submachine guns directly, and the rest were exported. Weapons were purchased in large batches by Switzerland, Bulgaria, Croatia, Estonia, and Germany also acquired it during the war years. Serial production under license in different years has been deployed in Denmark, Sweden, Switzerland.
Design features of the Suomi submachine gun
In general, the device of the Finnish submachine gun can be called typical for the first generation of such a weapon, which was developed on the basis of the German MP-18 and other early PP samples. As the main cartridge, Lahti initially chose the 9x19 mm Parabellum pistol cartridge, which was widespread in the world at that time. Despite the abundance of common places, the Finnish model differed from its predecessors and competitors in its own characteristics that could not be found in the weapons of other countries of the world.
A distinctive feature of the Finnish submachine guns was the high quality of production; metal-cutting machines were widely used in the creation of weapons. Good production is also noted by many modern researchers. True, this approach had a drawback. For example, the receiver was solid-milled, which led to an increase in the mass of the product. With a drum magazine "Suomi" weighed almost 6.5 kg. Also, the weapon could not be called technologically advanced in the sense that it was difficult to launch it into mass production in an all-out war. The cost of the submachine gun was also quite large, which left its mark on the volume of weapons production.
Structurally, the Suomi submachine gun consisted of an all-milled circular receiver, a solid wooden box, a barrel, a removable barrel casing and a trigger mechanism. In front of the trigger guard, Aimo Lahti placed a fuse that resembles an L-shaped piece. The fuse also served as a translator of fire modes.
Automatic reloading weapons worked by rolling back the free shutter from recoil when firing. Shooting from a submachine gun was carried out from an open bolt, while the drummer is fixed in the bolt cup, the barrel of the weapon is not locked during firing. To slow down the rate of fire required to increase the accuracy of fire, a vacuum shutter braking system was implemented in the model. The receiver, receiver cover and bolt were so tightly fitted that the bolt moved like a piston in a cylinder, there was almost no air breakthrough between the bolt and the walls of the receiver. And directly in the butt plate of the receiver, the designer placed a valve that released air only from the inside out.
Due to the system implemented by Lahti with a slowdown of the shutter, it was possible to reduce the mass of the shutter itself, as well as to increase the accuracy of fire from a submachine gun, especially with single shots. At the same time, the weapon was equipped with a sector sight, which was adjusted to fire up to 500 meters. Obviously, such values were excessive. Like most of the submachine guns of the Second World War, the weapons were really effective at a distance of no more than 200 meters, especially in the automatic mode of firing.
An important feature of the Finnish submachine gun, which distinguished it from competitors from other countries, was the removable barrel cover and the barrel itself. This design feature of the weapon gave the Finnish soldiers an advantage in battle, when it was easy to change and change the barrel itself. In the presence of spare barrels, this allowed the soldiers not to be afraid of possible overheating and weapon failure. The overheated barrel and casing could be easily changed right during the clash. The relatively long quick-detachable barrel (314 mm) also provided good ballistics to the weapon. For comparison: the PPSh had a barrel length of 269 mm.
It is important to emphasize here that some of the design decisions that made Suomi akin to light machine guns were dictated by the fact that the Finnish army lacked automatic weapons. At the initial stage of its creation, the new submachine gun was seriously considered as a light ersatz machine gun and a weapon of fire support for a squad in combat at short distances.
The magazine receiver on the Suomi submachine gun had an unusual "open" design at that time, which made it possible to use various large-capacity magazines. Several types of stores were created specifically for this model in Finland, among which the most famous was the drum magazine for 70 cartridges designed by Koskinen, which was put into service in 1936. Also, the weapon could be equipped with a disk magazine for 40 rounds and a box magazine for 20 rounds. Without a magazine and cartridges, the submachine gun weighed about 4.5 kg, with an equipped drum magazine for 70 rounds, the weight of the weapon was already approaching 6.5 kg.
Suomi submachine gun influenced the Red Army
The Suomi KP-31 submachine gun proved to be an ideal weapon for war in winter conditions, the weapon was unpretentious and reliable. This model was used by the Finnish military already during the Winter War of 1939-1940, and then more massively during the Second World War. At the same time, at the end of World War II, the Finns managed to use their submachine guns against their recent allies during the fleeting hostilities against German troops in the Lapland War.
The Finnish Suomi submachine gun made a great impression on the Red Army men and commanders of the Red Army, although at that time there were no more than four thousand KP-31 in the Finnish army. Despite their small numbers, the Finns defended quite skillfully, demonstrating a good level of training and education of personnel. Against this background, they used their few submachine guns quite skillfully, so that the Red Army drew attention to this automatic weapon. In the Soviet divisions that participated in the war, there were initially no submachine guns at all, which, however, was offset by the proliferation of semi-automatic and automatic rifles and the limited use of Fedorov assault rifles. Already during the conflict, the unit began to receive Degtyarev submachine guns (PPD). It was an example of feedback between the howling army on the one hand and the high command and the military-industrial complex on the other.
Acquaintance with Finnish tactics and feedback on the use of the Suomi submachine gun by the Finns became a real impetus for the intensification of the development of such weapons in the USSR, as well as the deployment of mass production and supply of the army with new weapons. At the same time, plans to establish mass production of submachine guns existed in the Soviet Union even before the Soviet-Finnish war, but this military conflict became a catalyst for this process, clearly confirming and proving the effectiveness of such weapons in combat conditions.
Also, based on the model of the Finnish submachine gun KP-31 in the USSR, in a short time, its own drum magazine was created for the later versions of the PPD and PPSh-41, designed for 71 rounds. This drum magazine will for many years become the hallmark of Soviet automatic weapons during the Second World War.
