- Years of issue – 1940 – 1945
- In total, 50,751 units were produced.
- Caliber – 120 mm
- Weight in firing position – 275 kg
- Barrel length – 1860 mm
- Calculation – 6 people
- Travel speed – up to 35 km / h
- Rate of fire – up to 15 rds / min
- The greatest firing range – 5900 m
- Direct shot range – 450 m
- Shooting angles:
- horizontal 6 °
- vertical + 45 ° + 80 °
120-mm regimental mortar was developed in SKB-4 at the plant number 7 “Arsenal” them. Frunze under the leadership of B.I. Shavyrin in 1938. It was a smooth-bore rigid system (without recoil devices), designed according to the “imaginary triangle” scheme. Officially, the 120-mm regimental mortar was adopted by the Red Army in February 1939, and its mass production began on September 1, after tests during the Soviet-Japanese armed conflict near the Khalkhin-Gol River.
The main structural elements of the regimental mortar were: a barrel, a two-legged carriage, a base plate and sights. The mortar barrel consisted of a pipe, a breech with a firing device, an obturating ring preventing the breakthrough of powder gases at the junction of the pipe with the breech, as well as a clamp with supports for laying and fixing the legs of the biped in a marching manner. In the muzzle of the channel there was a tapered chamfer to ensure the convenience of loading (to guide the stabilizer of the mine when lowering it into the barrel). The two-legged gun carriage gave the barrel the necessary vertical and horizontal guidance angles. Lifting, swiveling, leveling mechanisms and sights were mounted on it. Sharp impacts of the recoil force during a shot at a biped with sights were extinguished by a spring shock absorber. She softened the hard thrusts on the biped. The elevation angles of the mortar (vertical guidance) were provided by the installation of a two-legged carriage and a lifting mechanism. Horizontal aiming was carried out using a rotary mechanism and rearrangement of a two-legged gun carriage.
Unlike the 82-mm mortar, the base plate of the 120-mm mortar was an arched structure. Its top sheet was deep stamped. Stiffening ribs were welded to it from below, providing support for the slab on soft ground. The 120-mm mortars of the 1938 model were equipped with MP-41, MP-42, MPM-44 collimator sights and racks used to build a parallel fan. Firing from a mortar could be carried out both by the self-piercing cap of a mortar mine against the striker, and with the help of a firing mechanism, which made it possible to fire from cover with the help of a trigger cord. When firing with a samonakol, a maximum rate of fire of up to 15 rounds per minute was ensured, firing with a firing device, as a rule, was used to ensure the safety of the calculation when handling a powerful shot.
The mortar ammunition included 120-mm mortar mines: high-explosive steel fragmentation; high-explosive fragmentation cast iron; high-explosive steel; smoke cast iron; incendiary cast iron; lighting. The greatest firing range of a high-explosive fragmentation cast iron mine weighing 15.9 kg was 5900 m. Combat shots for a 120-mm mortar consisted of a mine, a fuse, a tail cartridge and 5 additional charges. The main charge was in the tail cartridge. Additional charges were put on the mine stabilizer tube and attached to it with a loop.To transport the mortar, a wheel drive with a suspension mechanism was developed, which was attached to the front end with ammunition. The mortar was transported by a four-horse harness. A wheeled mortar could also be transported in a trailer behind a car at a speed of up to 35 km / h. The mechanical thrust of a regimental mortar on a wheeled chassis could be carried out by a Komsomolets tracked tractor, a GAZ-AAA off-road truck and a GAZ-AA or GAZ-MM onboard vehicle. The mortar could fire at elevation angles of 45 ° and 80 °.The mine left craters up to 1.5 m deep. The initial flight speed of the mine reached 272 m / s. The calculation of the mortar consisted of 6 people: the commander, the gunner, the loader, the installer (he checked the mortar rack and set the fuse position on the mine) and 2 carriers (when transported on horseback, they were also sled).
By 1941, rifle divisions included 12 120-mm regimental mortars (one mortar battery of 4 mortars in each rifle regiment). Individual mortar battalions had 48 120-mm mortars each. By June 22, 1941, more than 3,000 regimental mortars were in service with the Red Army.
Since 1942, the regimental mortar was in service not only with rifle regiments and divisions, but also with tank, motorized rifle and motorized brigades, mechanized and rifle corps. In the brigades and regiments there were separate batteries of 120-mm mortars (4 each, and since 1943 – 6 mortars each), and in the corps and armies there were separate mortar regiments (2 – 3 mortar divisions of a three-battery composition, a total of 36 mortars). Since 1944, these regiments have become part of the mortar brigades of artillery divisions.
The 120-mm regimental mortar was intended to destroy enemy manpower and fire weapons, as well as to make passages in barbed wire and minefields. The steepness of the trajectory of the flight of mines made it possible to destroy closed targets that were not hit by small arms fire and artillery fire. The regimental mortar proved to be excellent during the Soviet-Finnish war of 1939-1940. Already the first battles showed that the 120-mm mortar is not only a “melee weapon”, but also the most powerful means of fire for the infantry, especially when there is a shortage of artillery. “There is no need to look for a better” janitor “for clearing trenches from a closely spaced enemy than a mortar,” wrote the Krasnaya Zvezda newspaper in 1943, calling mortars the mainstay of infantry in close combat.
The large losses of the material part of the Soviet artillery in the first months of the Great Patriotic War raised the question of the need for a sharp increase in the production of 120-mm mortars extremely sharply, since with a comparable mass of ammunition, the regimental mortar of the 1938 model was nine times lighter and about the same times cheaper than close to him in caliber 122-mm howitzer model 1938.
Along with connecting a number of enterprises to the production of 120-mm mortars, an increase in their output could also be achieved by simplifying the design and reducing the labor intensity and metal consumption. Therefore, B.I. Shavyrin receives the task to develop a simplified mortar, which, while maintaining the combat characteristics of a 120-mm mortar of the 1938 model, would have a simpler design, less laboriousness and high manufacturability.
A group of designers headed by B.I. Shavyrin in a short time developed a new design of a 120-mm regimental mortar, which, unlike the 1938 model of the year, had a simplified barrel with a screwed breech, a simpler shock absorber with increased travel, as well as a modified design of the biped, swivel and lifting mechanisms. The simplified mortar was not equipped with a wheel drive and front end, so it could be transported in the back of a car along with the crew and ammunition.The simplified 1941 mortar was not inferior to the standard one in terms of combat characteristics, and in some respects even surpassed it. Its production was mastered at the end of 1941, which made it possible to increase the production of mortars by 1.8 times using the same equipment. The labor intensity of production was reduced by almost half, and the consumption of materials – by 26%. In 1943, the 120-mm regimental mortar underwent another modernization, which was carried out by the design team led by A.A. Kotov. Its goal was, while maintaining and increasing the combat and operational characteristics, to make the design of the mortar even more technological and less laborious.
First of all, the mortar barrel was improved. The firing mechanism built into the barrel breech has been simplified again. In addition, if earlier, to replace a broken drummer, it was necessary to disassemble the mortar and unscrew the breech from the barrel, now the new design of the firing mechanism made it possible to replace the drummer without disassembling the mortar, which was especially important in a combat situation. Another important innovation was the original double-loading fuse, designed by N.M. Afanasyev.The combat operation of muzzle-loading mortars revealed their one of the most significant drawbacks – the possibility of double or re-loading the mortar from the muzzle, which occurred during intensive firing in combat conditions – due to the carelessness of the combat crew (mainly when firing with rapid fire or when resuming firing after a long break) , when the loader could not notice the shot from his mortar and send it into the barrel after the first second mine. This could also happen with a misfire; weak piercing of the primer of the first mine;a protracted shot or the failure of a mine to reach the striker due to contamination of the barrel bore, the mine body, or foreign objects entering the barrel bore. A shot fired from a mortar loaded with two mines inevitably led to the death of the crew if it was not in cover and the destruction of the mortar. Therefore, the mortars were equipped with very reliable automatic double-loading fuses, which were worn on the muzzle of the barrel. Now the fuse blade prevented the second mine from being sent into the barrel after the first.
Double-loading fuses worked flawlessly when firing mines of any type; on all charges provided for this mortar; at any angles of elevation and horizontal guidance; at different rates of fire; from firing positions on any ground. Since 1943, the 120-mm regimental mortar was produced only with such a fuse. In addition, the mortar was equipped with shock absorbers with a longer spring travel and a swinging sight, which simplified the leveling mechanism. A new suspension wheel system has also been developed.
The mortar of the 1943 model was produced until the end of the war and, along with the 120-mm mortars of the 1938 and 1941 model, proved to be an extremely effective and mobile weapon. If at the beginning of World War II mortars were considered as a means of direct support for the infantry, by the end of it they turned into one of the main types of artillery. The combat work of the 120-mm regimental mortar is well illustrated by the example of the calculation of the Shumov brothers, whose glory resounded throughout the Leningrad front. Since 1942, six brothers have fought in one crew of a 120-mm mortar.They fired so that there were eighteen mines in the air at the same time, i.e. when the first mine exploded at the enemy’s positions, the twentieth mine was dropped into the barrel, and eighteen were already flying at the enemy. Fighting off furious enemy attacks, clearing the way for the infantry, they fired 13,986 shots from their mortar, destroying over 400 enemy soldiers and officers, destroying 29 bunkers and dugouts, suppressing the fire of 13 machine guns and 11 mortars. The Shumovs’ mortar crew traveled over 800 km along the roads of the war. He participated in the summer battles of 1943 in the Sinyavino area, in the defeat of the enemy near Leningrad in January 1944 and in the liberation of the Baltic. In the battles for the Motherland, Vasily, Semyon and Ivan, Alexander, Luka and Avksentiy Shumovs returned home.
120-mm regimental mortars were produced during the Great Patriotic War at factories: No. 4 named after. Voroshilov (Krasnoyarsk), No. 7 “Arsenal” them. Frunze (Leningrad), No. 221 “Barricades” (Stalingrad), “Engine of the Revolution” (Gorky) and a number of others.
In 1940 – 1945, the Red Army received 50,751 120-mm regimental mortars of all modifications.