152 mm mortar M1931 (NM)
Encyclopedia
152 mm mortar M1931 (NM) was a 152.4 mm (6 inch) artillery piece originally developed by the German
arms manufacturer Rheinmetall
. The gun was produced in limited numbers in the Soviet Union
and saw action with the Soviet Army
in World War II
. A modified version of the design was also adopted in Germany
, as 15 cm sIG 33.
fitted with horizontal sliding breech
. The recoil
system consisted of hydraulic compressor and hydropneumatic recuperator, both mounted in the gun cradle. The recoil length was fixed. The carriage was of box trail type, with equilibrator, suspension and a folding spade. Metal wheels had removable rubber tires. The gun was equipped with a shield.
The first 152 mm divisional mortar for the RKKA was developed in by Kirov Plant
in 1930. The gun weighed about 1,500 kg. It utilized a breechblock and other elements of the 152 mm fortress howitzer M1909. It is not clear whether the piece was ever completed.
From late 1920s, USSR looked for foreign assistance in modernizing its artillery. Germany could and was willing to offer such assistance. The cooperation with USSR allowed Germany, constrained by the Treaty of Versailles
, an opportunity to proceed with arms development. In 1929, German arms manufacturer Rheinmetall
created a dummy company Butast for contacts with USSR. In accordance with the Sovnarkom decision from 8 August 1930, on 28 August in Berlin a secret agreement was signed. Germans undertook to help USSR with production of six artillery systems:
For $1,125 mil. Rheinmetall supplied pre-production samples, documentation and parts from which in USSR a few pieces of each type could be assembled.
Among other pieces, Rheinmetall brought to USSR eight 152 mm mortars. The guns went through ground trials in June 1931 and were tested by the army in August 1932. The weapon was adopted as 152 mm mortar M1931. In the contemporary documents it is often referred to as N or NM.
The gun was in production from 1932 to 1935 at Plant no. 172
(MZM - Motovilikha Machinery Plant; ). The production continuously lagged behind the schedule. In 1932, 5 mortars were manufactured; in 1933 - 50, in 1934 – 59, and in 1935 – 15 pieces. During the production period the gun was repeatedly modified; for example, the barrel of was lengthened by 65 mm.
In 1937 a modernized variant was developed. This variant, designated ML-21, reached factory trials on 27 March 1937 and ground and army trials in 1938. The trials revealed some minor defects. The ML-21 was never adopted.
Meanwhile, in Germany a modified variant of the original Rheinmetall design was adopted as 15 cm sIG 33.
tank chassis. The resulting self-propelled gun, designated SU-5-3, successfully underwent factory trials in 1934 and even took part in a parade at the Red Square
. However, in 1935 the project was cancelled, because the T-26 chassis was considered too weak for a 152 mm piece. The fate of the prototype vehicle is unknown. There is an unconfirmed information that it was rebuilt as SU-5-2, armed with 122 mm howitzer M1910/30.
artillery, which from 1935 to June 1941 included a battalion
of 152 mm howitzers. On 1 November 1936 RKKA possessed 104 pieces (including three practical and one non-operational). By June 1941 only 51 of them remained and, according to the historian M. Svirin, all these were in mobilization reserve. Some pieces saw combat early in the German-Soviet War. In 1942, new ballistic tables for the mortar were released.
, a cheaper, lighter weapon with slightly longer range, but on the other hand less powerful, less accurate and less versatile. Eventually, a need for a divisional weapon more powerful than a 122 mm howitzer became apparent; in 1943 the RKKA adopted another infantry mortar, the 160 mm divisional mortar MT-13
, which was similar to the NM in terms of weight, range and shell weight.
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
arms manufacturer Rheinmetall
Rheinmetall
Rheinmetall AG is a German automotive and defence company with factories in Düsseldorf, Kassel and Unterlüß. The company has a long tradition of making guns and artillery pieces...
. The gun was produced in limited numbers in the Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
and saw action with the Soviet Army
Soviet Army
The Soviet Army is the name given to the main part of the Armed Forces of the Soviet Union between 1946 and 1992. Previously, it had been known as the Red Army. Informally, Армия referred to all the MOD armed forces, except, in some cases, the Soviet Navy.This article covers the Soviet Ground...
in World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. A modified version of the design was also adopted in Germany
Nazi Germany
Nazi Germany , also known as the Third Reich , but officially called German Reich from 1933 to 1943 and Greater German Reich from 26 June 1943 onward, is the name commonly used to refer to the state of Germany from 1933 to 1945, when it was a totalitarian dictatorship ruled by...
, as 15 cm sIG 33.
Description
The gun had monobloc barrelGun barrel
A gun barrel is the tube, usually metal, through which a controlled explosion or rapid expansion of gases are released in order to propel a projectile out of the end at a high velocity....
fitted with horizontal sliding breech
Breechblock
A breechblock is the part of the firearm action that closes the breech of a weapon at the moment of firing....
. The recoil
Recoil
Recoil is the backward momentum of a gun when it is discharged. In technical terms, the recoil caused by the gun exactly balances the forward momentum of the projectile and exhaust gasses, according to Newton's third law...
system consisted of hydraulic compressor and hydropneumatic recuperator, both mounted in the gun cradle. The recoil length was fixed. The carriage was of box trail type, with equilibrator, suspension and a folding spade. Metal wheels had removable rubber tires. The gun was equipped with a shield.
Development and production
Kirov Plant
The Kirov Plant Kirov Factory or Leningrad Kirov Plant is a major Russian machine-building plant in St. Petersburg, Russia....
in 1930. The gun weighed about 1,500 kg. It utilized a breechblock and other elements of the 152 mm fortress howitzer M1909. It is not clear whether the piece was ever completed.
From late 1920s, USSR looked for foreign assistance in modernizing its artillery. Germany could and was willing to offer such assistance. The cooperation with USSR allowed Germany, constrained by the Treaty of Versailles
Treaty of Versailles
The Treaty of Versailles was one of the peace treaties at the end of World War I. It ended the state of war between Germany and the Allied Powers. It was signed on 28 June 1919, exactly five years after the assassination of Archduke Franz Ferdinand. The other Central Powers on the German side of...
, an opportunity to proceed with arms development. In 1929, German arms manufacturer Rheinmetall
Rheinmetall
Rheinmetall AG is a German automotive and defence company with factories in Düsseldorf, Kassel and Unterlüß. The company has a long tradition of making guns and artillery pieces...
created a dummy company Butast for contacts with USSR. In accordance with the Sovnarkom decision from 8 August 1930, on 28 August in Berlin a secret agreement was signed. Germans undertook to help USSR with production of six artillery systems:
- 37 mm anti-tank gun37 mm anti-tank gun M1930 (1-K)37-mm anti-tank gun model 1930 was a Soviet light anti-tank gun used in the first stage of the German-Soviet War.-Description:1-K was a Soviet anti-tank gun initially developed by the German company Rheinmetall. The gun was closely related to the German PaK 35/36...
- 76 mm anti-aircraft gun
- 152 mm mortar
- 152 mm howitzer
- 20 mm anti-aircraft autocannon
- 37 mm anti-aircraft autocannon
For $1,125 mil. Rheinmetall supplied pre-production samples, documentation and parts from which in USSR a few pieces of each type could be assembled.
Among other pieces, Rheinmetall brought to USSR eight 152 mm mortars. The guns went through ground trials in June 1931 and were tested by the army in August 1932. The weapon was adopted as 152 mm mortar M1931. In the contemporary documents it is often referred to as N or NM.
The gun was in production from 1932 to 1935 at Plant no. 172
Motovilikha Plants
Motovilikha Plants is a Russian metallurgical and military equipment manufacturer. The full official name of the company is Open stock venture for special machinery and metallurgy "Motovilikha Plants" .*...
(MZM - Motovilikha Machinery Plant; ). The production continuously lagged behind the schedule. In 1932, 5 mortars were manufactured; in 1933 - 50, in 1934 – 59, and in 1935 – 15 pieces. During the production period the gun was repeatedly modified; for example, the barrel of was lengthened by 65 mm.
In 1937 a modernized variant was developed. This variant, designated ML-21, reached factory trials on 27 March 1937 and ground and army trials in 1938. The trials revealed some minor defects. The ML-21 was never adopted.
Meanwhile, in Germany a modified variant of the original Rheinmetall design was adopted as 15 cm sIG 33.
Variants
- The original variant, supplied from Germany (8 pieces).
- The Soviet mass production variant with longer barrel (129 pieces).
- ML-21 (3 pieces).
Self-propelled mounts
The NM was experimentally mounted on T-26T-26
The T-26 tank was a Soviet light infantry tank used during many conflicts of the 1930s as well as during World War II. It was a development of the British Vickers 6-Ton tank and is widely considered one of the most successful tank designs of the 1930s....
tank chassis. The resulting self-propelled gun, designated SU-5-3, successfully underwent factory trials in 1934 and even took part in a parade at the Red Square
Red Square
Red Square is a city square in Moscow, Russia. The square separates the Kremlin, the former royal citadel and currently the official residence of the President of Russia, from a historic merchant quarter known as Kitai-gorod...
. However, in 1935 the project was cancelled, because the T-26 chassis was considered too weak for a 152 mm piece. The fate of the prototype vehicle is unknown. There is an unconfirmed information that it was rebuilt as SU-5-2, armed with 122 mm howitzer M1910/30.
Employment
The NM was employed in divisionalDivision (military)
A division is a large military unit or formation usually consisting of between 10,000 and 20,000 soldiers. In most armies, a division is composed of several regiments or brigades, and in turn several divisions typically make up a corps...
artillery, which from 1935 to June 1941 included a battalion
Battalion
A battalion is a military unit of around 300–1,200 soldiers usually consisting of between two and seven companies and typically commanded by either a Lieutenant Colonel or a Colonel...
of 152 mm howitzers. On 1 November 1936 RKKA possessed 104 pieces (including three practical and one non-operational). By June 1941 only 51 of them remained and, according to the historian M. Svirin, all these were in mobilization reserve. Some pieces saw combat early in the German-Soviet War. In 1942, new ballistic tables for the mortar were released.
Summary
Despite some advantages of the NM, notably its versatility and very light weight for a 152-mm piece, the production was cancelled after a limited number of guns were built. According to M. Svirin, complexity of the design was the main reason. For example, Soviet ordnance plants experienced major problems with production of sliding breechblocks. Also, the NM poorly fitted the Soviet artillery doctrine, mainly because of its range - too short for a divisional gun. The related German design - the 15 cm sIG 33 - was employed as a regimental weapon; it was somewhat heavy for a regimental piece. In the RKKA, the niche of heavy regimental weapon was filled by a 120 mm infantry mortarM1938 mortar
The Soviet M1938 120-millimeter mortar was the first modern 120 mm mortar developed by any country, entering production in 1939. The Red Army made significant use of its heavy caliber by treating it as an artillery piece in World War II. The Germans were impressed by the weapon and adopted it...
, a cheaper, lighter weapon with slightly longer range, but on the other hand less powerful, less accurate and less versatile. Eventually, a need for a divisional weapon more powerful than a 122 mm howitzer became apparent; in 1943 the RKKA adopted another infantry mortar, the 160 mm divisional mortar MT-13
160mm Mortar M1943
The Soviet 160 mm Mortar M1943 was a smoothbore breech loading heavy mortar which fired a massive 160 mm bomb. The M1943 was the heaviest mortar used by Soviet troops in World War II. Around 535 of these weapons were fielded with Soviet forces during the war...
, which was similar to the NM in terms of weight, range and shell weight.
Ammunition
The mortar used separate loading ammunition. The cartridge case could contain five different propellant charges. In addition to an old HE shell, two new HE-Frag shells were developed. The "draft 4139" shell was produced in limited numbers and was no longer used by 1934.| Available ammunition | |||||
| Type | Model | Weight, kg | HE weight, kg | Muzzle velocity, m/s | Range, m |
| High explosive and fragmentation shells | |||||
| HE-Fragmentation | draft 4139 | 38.33 | 7.612 | ||
| HE-Fragmentation | draft 3905 / OF-521 | 38.21 | 7.69 | 250 | 5,285 |
| HE, old | F-533 | 40.95 | 7.06 | 241 | 5,041 |
| Chemical shells | |||||
| Fragmentation-chemical | OH-521 | ||||
| Chemical | H-521 | ||||