ML-20
Encyclopedia
The 152 mm howitzer-gun M1937 (ML-20) (), was a Soviet
gun-howitzer
. The gun was developed by the design bureau of the plant no 172, headed by F. F. Petrov
, as a deep upgrade of the 152-mm gun M1910/34
, in turn based on the 152-mm siege gun M1910, a pre-World War I
design by Schneider
. It was in production from 1937 to 1946. The ML-20 saw action in World War II
, mainly as a corps / army level artillery piece of the Soviet Army
. Captured guns were employed by Wehrmacht
and the Finnish Army
. Post World War II, the ML-20 saw combat in numerous conflicts during the mid to late twentieth century.
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The ML-20 was officially classified as howitzer-gun, i.e. an artillery system which combines characteristics of a howitzer
and (to lesser extent) of a gun and therefore can be used in both roles. This universality was achieved by wide range of elevation angles and by using separate loading with 13 different propellant loads. The gun was fitted with both telescopic sight for direct fire and panoramic sight for an indirect one. For ballistic
calculations and meteorological corrections a special mechanical device was developed. The device, called meteoballistic summator, consisted of a specialized slide rule
and a pre-calculated table. After World War II similar devices were introduced for other types of guns.
The barrel
was either monobloc or built-up. Some sources indicate that a third type - with loose liner
- also existed. To soften recoil
, a large slotted muzzle brake
was fitted. The breechblock was of interrupted screw
type, with forced extraction of cartridge
during opening. A safety lock prevented opening of the breechblock before the shot; if there was a need to remove a shell, the lock had to be disabled. To assist loading when the barrel was set to high elevation angle, the breach was equipped with cartridge holding mechanism. The gun was fired by pulling a trigger cord.
The recoil system consisted of a hydraulic
buffer and hydropneumatic recuperator. Each held 22 litre
s of liquid. Pressure in the recuperator reached 45 atm
.
The carriage was of split trail type, with shield and balancing mechanism, leaf spring
suspension and steel wheels with rubber tire
s (some early production pieces received spoked wheels with solid tires from M1910/34). During transportation the barrel was usually retracted. The gun could also be towed with the barrel in its normal position, but in this case the transportation speed was limited, about 4–5 km/h (compared to 20 km/h with barrel pulled back). The gun could be set up for combat in 8–10 minutes. The carriage, designated 52-L-504A, was also used in the 122-mm gun model 1931/37 (A-19).
(RKKA) inherited from the Imperial Russian Army a 152-mm siege gun M1910, developed by Schneider
. The gun was modernized twice in 1930s, resulting in the 152-mm gun M1910/30
and the 152-mm gun M1910/34
. However, its mobility, maximum elevation and speed of traverse still needed improvement. In 1935-36 the No. 172 Plant
in Motovilikha tried to continue the modernization works, but the Main Artillery Directorate (GAU) insisted on more significant upgrade.
Consequently, the design bureau of the plant developed two guns ML-15 and ML-20. While the former project was initiated by GAU, the latter started as private development; the team working on it was led by F. F. Petrov
. Both guns used barrel and recoil system of the M1910/34. The ML-20 also inherithed from the older gun its wheels, suspension and trails.
The ML-15 reached ground tests in April 1936, was returned for revision and was tested again in March 1937, this time successfully. The ML-20 went through ground tests in December 1936 and through army tests next year. After some defects (mostly in carriage) were eliminated, the ML-20 was recommended for production and on 22 September 1937 it was adopted as 152-mm howitzer-gun model 1937 .
It is not clear why the ML-20 was preferred. The ML-15 was lighter (about 500 kg less in combat position, 600 kg in traveling position) and more mobile (maximum transportation speed 45 km/h). On the negative side, the ML-15 had more sophisticated carriage (however, the final version of the ML-20 carriage incorporated some features of the ML-15). Some sources claim that the choice was made because of the economic factor - the ML-20 was more similar to the M1910/34, meaning less arrangements for production.
s SU-152
and ISU-152
. The ML-20 was eventually replaced by the D-20 152 mm gun with identical ballistics, which entered production in 1956.
Smaller production rates toward the end of the war were caused by two reasons. First, most of the barrels produced in these years were ML-20S. Second, after Germans fielded heavy tanks the plant was ordered to increase production of A-19 122 mm guns instead of some ML-20.
artillery. Together with the 122-mm gun A-19 it formed a so-called "corps duplex". In 1940-41 there were three types of corps artillery regiment
s:
Soon after the outbreak of Operation Barbarossa
, the corps artillery was eliminated (as rifle corps themselves were eliminated). It was restored later in the war. The new corps artillery regiments were supposed to be armed with 122-mm guns or 152-mm howitzers, but some memoir
s mention that the ML-20 was also used.
From 1943 the gun was employed by artillery regiments of armies
. Such regiment had 18 ML-20s. Guard armies from early 1945 had artillery brigade
with 36 ML-20s.
The ML-20 also used by artillery regiments (24 pieces) and brigades (36 pieces) of the Reserve of the Main Command.
It was primarily used for indirect fire against enemy personnel, fortification
s and key objects in the near rear. Heavy fragments of the OF-540 HE-Fragmentation shell were capable of piercing armour up to 20–30 mm thick, making a barrage dangerous to thinly armored vehicles and to some extent to heavier armoured ones as the fragments could damage chassis, sights or other elements; sometimes a close expolsion caused damage inside a vehicle even though the armour remained intact. Direct hit of a shell often resulted in tearing away a turret of a medium tank or jamming it in case of a heavy tank.
The gun was also equipped with armour-piercing shells for direct fire against armoured targets. Although not an ideal anti-tank gun because of its large size, slow traverse and slow rate of fire, in 1943 the ML-20 was one of a few guns effective against new German
tanks. For example, the glacis armour of the heavy Tiger I
could be penetrated from about a kilometer.
The first combat use of the ML-20 was in the Battle of Khalkhin Gol
, in limited numbers. It also saw combat in the Winter War
against the Mannerheim Line
fortifications. The gun proceeded to be used throughout the second world war.
Excellent characteristics of the gun, including reliability and ease of maintenance, allowed it to remain in service with the Soviet Army for a long time after the war.
. The gun was adopted by Germans as 15.2 cm KH.433/1(r). From February 1943 Germans manufactured an ammunition for the gun.
The Finnish Army
captured 37 guns of the type in 1941-44 and received additional 27 from Germany. These guns were adopted as 152 H 37. A number of barrels were mated with carriages of A-19 to create 152 H 37-31. While the gun was generally liked, the Finnish Army didn't possess enough prime movers suitable for towing such a massive piece. As a result, some of the guns were assigned to coastal artillery
. Two pieces were captured back by the Red Army. A number of these guns were modernized in 1988 and as of 2004 still remain in reserve as 152 H 88-37. (all of the 152 H 88
series are being withdrawn as of 2007).
After the war the ML-20 was widely exported to Warsaw Pact
allies and to many states in Asia and Africa (in some of those states the gun still remains in service). It was adopted by Egypt
and Syria
and therefore saw action in Arab-Israeli conflict. In 2002 a TV documentary featured ML-20 employed by the Afghan Northern Alliance forces against the Taliban fighters; it seems likely that the guns were initially supplied to the Najibullah
's regime.
Except the basic variant, the only variant to reach mass production was the ML-20S, developed for use in self-propelled guns, with differently placed controls for easier operation in small enclosed compartment.
had range of 13.3 km), which often allowed it to shell positions of enemy artillery while remaining immune to enemy fire. Its advantage over the latter was in weight and cost, and therefore in mobility and production rate. For example, the German 15 cm K 18 with range of 24.8 km weighed 12.5 tons and only 101 pieces were built; of the excellent 17 cm K 18 (23.4 t, 29.6 km) 338 pieces were manufactured; lighter 10.5 cm sK 18 (5.6 t, 19.1 km) was more common (2,135 pieces) but its 15 kg shell was much less powerful than a 44 kg shell of ML-20. German attempts to produce an analogue to the ML-20 were unsuccessful. The 15 cm sFH 40 was never produced due to construction defects; the 15 сm sFH 42 had insufficient range and only 46 pieces were built. In 1943 and 1944 Wehrmacht announced requirements for a 15 cm howitzer with a range of 18 km, but none reached production.
Of other guns with more or less similar characteristics, there were French
155 mm guns model 1917 and 1918
with longer range, but some 3.5 tons heavier (as was the US 155 mm M1 howitzer
). The Czechoslovakian howitzer K4
(used by Germans as 15 cm sFH 37(t)) was about 2 tons lighter, but with range more than 2 km shorter and only 178 pieces were built. The British
BL 5.5 inch (140 mm) gun
also had shorter range.
The main shortcomings of the ML-20 were its weight and limited mobility. As the experience of the ML-15 project suggests, the gun could be made somewhat lighter and more suitable for high-speed transportation. The use of a muzzle brake can be seen as a minor flaw: while softening the recoil and thus allowing the use of a lighter carriage, a muzzle brake has the disadvantage of redirecting some of the gases that escape the barrel toward the ground, where they can raise dust, potentially revealing the gun position. But when the ML-20 was developed, muzzle brakes were already a common design element in artillery pieces of that class.
ML-20s are on display in a number of military museums. Among other places, the gun can be seen:
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....
gun-howitzer
Howitzer
A howitzer is a type of artillery piece characterized by a relatively short barrel and the use of comparatively small propellant charges to propel projectiles at relatively high trajectories, with a steep angle of descent...
. The gun was developed by the design bureau of the plant no 172, headed by F. F. Petrov
Fyodor Petrov
Fyodor Fyodorovich Petrov was a Soviet artillery designer....
, as a deep upgrade of the 152-mm gun M1910/34
152-mm gun M1910/34
152-mm gun model 1910/34 was a Soviet 152.4 mm heavy gun, a modernization of the 152-mm gun M1910/30, which in turn was based on 152-mm siege gun M1910.-Description:...
, in turn based on the 152-mm siege gun M1910, a pre-World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...
design by Schneider
Schneider Electric
Schneider Electric is a French global company. It was founded in 1836 by two brothers, Eugène and Adolphe Schneider.In the first part of the 20th century, Schneider et Cie associated itself with Westinghouse Systems, a major international electrical group at the time. The group began manufacturing...
. It was in production from 1937 to 1946. The ML-20 saw action 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...
, mainly as a corps / army level artillery piece of 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...
. Captured guns were employed by Wehrmacht
Wehrmacht
The Wehrmacht – from , to defend and , the might/power) were the unified armed forces of Nazi Germany from 1935 to 1945. It consisted of the Heer , the Kriegsmarine and the Luftwaffe .-Origin and use of the term:...
and the Finnish Army
Finnish Army
The Finnish Army is the land forces branch of the Finnish Defence Forces.Today's Army is divided into six branches: the infantry , field artillery, anti-aircraft artillery, engineers, signals, and materiel troops.-History of the Finnish Army:Between 1809 and 1917 Finland was an autonomous part of...
. Post World War II, the ML-20 saw combat in numerous conflicts during the mid to late twentieth century.
Description
Howitzer
A howitzer is a type of artillery piece characterized by a relatively short barrel and the use of comparatively small propellant charges to propel projectiles at relatively high trajectories, with a steep angle of descent...
and (to lesser extent) of a gun and therefore can be used in both roles. This universality was achieved by wide range of elevation angles and by using separate loading with 13 different propellant loads. The gun was fitted with both telescopic sight for direct fire and panoramic sight for an indirect one. For ballistic
Ballistics
Ballistics is the science of mechanics that deals with the flight, behavior, and effects of projectiles, especially bullets, gravity bombs, rockets, or the like; the science or art of designing and accelerating projectiles so as to achieve a desired performance.A ballistic body is a body which is...
calculations and meteorological corrections a special mechanical device was developed. The device, called meteoballistic summator, consisted of a specialized slide rule
Slide rule
The slide rule, also known colloquially as a slipstick, is a mechanical analog computer. The slide rule is used primarily for multiplication and division, and also for functions such as roots, logarithms and trigonometry, but is not normally used for addition or subtraction.Slide rules come in a...
and a pre-calculated table. After World War II similar devices were introduced for other types of guns.
The barrel
Gun 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....
was either monobloc or built-up. Some sources indicate that a third type - with loose liner
Liner
Liner or LINER may refer to:In line drawing:* Eye liner, a type of makeup* Liner, a sable brush used by coach paintersIn linings:...
- also existed. To soften 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...
, a large slotted muzzle brake
Muzzle brake
Muzzle brakes and recoil compensators are devices that are fitted to the muzzle of a firearm or cannon to redirect propellant gases with the effect of countering both recoil of the gun and unwanted rising of the barrel during rapid fire...
was fitted. The breechblock was of interrupted screw
Interrupted screw
An interrupted screw or interrupted thread is a mechanical device typically used in the breech of artillery guns. It was invented circa 1845....
type, with forced extraction of cartridge
Cartridge (firearms)
A cartridge, also called a round, packages the bullet, gunpowder and primer into a single metallic case precisely made to fit the firing chamber of a firearm. The primer is a small charge of impact-sensitive chemical that may be located at the center of the case head or at its rim . Electrically...
during opening. A safety lock prevented opening of the breechblock before the shot; if there was a need to remove a shell, the lock had to be disabled. To assist loading when the barrel was set to high elevation angle, the breach was equipped with cartridge holding mechanism. The gun was fired by pulling a trigger cord.
The recoil system consisted of a hydraulic
Hydraulics
Hydraulics is a topic in applied science and engineering dealing with the mechanical properties of liquids. Fluid mechanics provides the theoretical foundation for hydraulics, which focuses on the engineering uses of fluid properties. In fluid power, hydraulics is used for the generation, control,...
buffer and hydropneumatic recuperator. Each held 22 litre
Litre
pic|200px|right|thumb|One litre is equivalent to this cubeEach side is 10 cm1 litre water = 1 kilogram water The litre is a metric system unit of volume equal to 1 cubic decimetre , to 1,000 cubic centimetres , and to 1/1,000 cubic metre...
s of liquid. Pressure in the recuperator reached 45 atm
Atmosphere (unit)
The standard atmosphere is an international reference pressure defined as 101325 Pa and formerly used as unit of pressure. For practical purposes it has been replaced by the bar which is 105 Pa...
.
The carriage was of split trail type, with shield and balancing mechanism, leaf spring
Leaf spring
Originally called laminated or carriage spring, a leaf spring is a simple form of spring, commonly used for the suspension in wheeled vehicles...
suspension and steel wheels with rubber tire
Tire
A tire or tyre is a ring-shaped covering that fits around a wheel rim to protect it and enable better vehicle performance by providing a flexible cushion that absorbs shock while keeping the wheel in close contact with the ground...
s (some early production pieces received spoked wheels with solid tires from M1910/34). During transportation the barrel was usually retracted. The gun could also be towed with the barrel in its normal position, but in this case the transportation speed was limited, about 4–5 km/h (compared to 20 km/h with barrel pulled back). The gun could be set up for combat in 8–10 minutes. The carriage, designated 52-L-504A, was also used in the 122-mm gun model 1931/37 (A-19).
Development history
Among other artillery pieces the Red ArmyRed Army
The Workers' and Peasants' Red Army started out as the Soviet Union's revolutionary communist combat groups during the Russian Civil War of 1918-1922. It grew into the national army of the Soviet Union. By the 1930s the Red Army was among the largest armies in history.The "Red Army" name refers to...
(RKKA) inherited from the Imperial Russian Army a 152-mm siege gun M1910, developed by Schneider
Schneider Electric
Schneider Electric is a French global company. It was founded in 1836 by two brothers, Eugène and Adolphe Schneider.In the first part of the 20th century, Schneider et Cie associated itself with Westinghouse Systems, a major international electrical group at the time. The group began manufacturing...
. The gun was modernized twice in 1930s, resulting in the 152-mm gun M1910/30
152-mm gun M1910/30
152-mm gun model 1910/30 was a Soviet gun, a modernization of World War I era 152-mm siege gun M1910. The gun was briefly used by RKKA in the German-Soviet War.-Description:...
and the 152-mm gun M1910/34
152-mm gun M1910/34
152-mm gun model 1910/34 was a Soviet 152.4 mm heavy gun, a modernization of the 152-mm gun M1910/30, which in turn was based on 152-mm siege gun M1910.-Description:...
. However, its mobility, maximum elevation and speed of traverse still needed improvement. In 1935-36 the No. 172 Plant
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" .*...
in Motovilikha tried to continue the modernization works, but the Main Artillery Directorate (GAU) insisted on more significant upgrade.
Consequently, the design bureau of the plant developed two guns ML-15 and ML-20. While the former project was initiated by GAU, the latter started as private development; the team working on it was led by F. F. Petrov
Fyodor Petrov
Fyodor Fyodorovich Petrov was a Soviet artillery designer....
. Both guns used barrel and recoil system of the M1910/34. The ML-20 also inherithed from the older gun its wheels, suspension and trails.
The ML-15 reached ground tests in April 1936, was returned for revision and was tested again in March 1937, this time successfully. The ML-20 went through ground tests in December 1936 and through army tests next year. After some defects (mostly in carriage) were eliminated, the ML-20 was recommended for production and on 22 September 1937 it was adopted as 152-mm howitzer-gun model 1937 .
It is not clear why the ML-20 was preferred. The ML-15 was lighter (about 500 kg less in combat position, 600 kg in traveling position) and more mobile (maximum transportation speed 45 km/h). On the negative side, the ML-15 had more sophisticated carriage (however, the final version of the ML-20 carriage incorporated some features of the ML-15). Some sources claim that the choice was made because of the economic factor - the ML-20 was more similar to the M1910/34, meaning less arrangements for production.
Production history
The gun was in production in 1937-46. 6,884 guns were manufactured and about 4,000 ML-20S barrels for using in self-propelled gunSelf-propelled gun
A self-propelled gun is form of self-propelled artillery, and in modern use is usually used to refer to artillery pieces such as howitzers....
s SU-152
SU-152
The SU-152 was a Soviet heavy self-propelled heavy howitzer used during World War II.It mounted a 152 mm gun-howitzer on the chassis of a KV-1S heavy tank. Later production used IS tank chassis and was re-designated as ISU-152...
and ISU-152
ISU-152
ISU-152 was a Soviet multirole fully enclosed and armored self-propelled gun developed and used during World War II, with a subsequent use, mainly in the Soviet military, till the 1970s.-History:...
. The ML-20 was eventually replaced by the D-20 152 mm gun with identical ballistics, which entered production in 1956.
| Production of МL-20s, pcs. | |||||||||||
| Year | 1937 | 1938 | 1939 | 1940 | 1941 | 1942 | 1943 | 1944 | 1945 | 1946 | Total |
| Produced, pcs. | 148 | 500 | 567 | 901 | 1,342 | 1,809 | 1,002 | 275 | 325 | 15 | 6,884 |
Smaller production rates toward the end of the war were caused by two reasons. First, most of the barrels produced in these years were ML-20S. Second, after Germans fielded heavy tanks the plant was ordered to increase production of A-19 122 mm guns instead of some ML-20.
Organization and employment
Red Army
The ML-20 was originally intended for corpsCorps
A corps is either a large formation, or an administrative grouping of troops within an armed force with a common function such as Artillery or Signals representing an arm of service...
artillery. Together with the 122-mm gun A-19 it formed a so-called "corps duplex". In 1940-41 there were three types of corps artillery regiment
Regiment
A regiment is a major tactical military unit, composed of variable numbers of batteries, squadrons or battalions, commanded by a colonel or lieutenant colonel...
s:
- With two battalionBattalionA 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...
s of ML-20 and one of either A-19 or 107-mm guns (a total of 24 ML-20s). - With two battalions of ML-20 and two of either A-19 or 107-mm guns (a total of 24 ML-20s).
- With three battalions of ML-20 (a total of 36 ML-20s).
Soon after the outbreak of Operation Barbarossa
Operation Barbarossa
Operation Barbarossa was the code name for Germany's invasion of the Soviet Union during World War II that began on 22 June 1941. Over 4.5 million troops of the Axis powers invaded the USSR along a front., the largest invasion in the history of warfare...
, the corps artillery was eliminated (as rifle corps themselves were eliminated). It was restored later in the war. The new corps artillery regiments were supposed to be armed with 122-mm guns or 152-mm howitzers, but some memoir
Memoir
A memoir , is a literary genre, forming a subclass of autobiography – although the terms 'memoir' and 'autobiography' are almost interchangeable. Memoir is autobiographical writing, but not all autobiographical writing follows the criteria for memoir set out below...
s mention that the ML-20 was also used.
From 1943 the gun was employed by artillery regiments of armies
Army
An army An army An army (from Latin arma "arms, weapons" via Old French armée, "armed" (feminine), in the broadest sense, is the land-based military of a nation or state. It may also include other branches of the military such as the air force via means of aviation corps...
. Such regiment had 18 ML-20s. Guard armies from early 1945 had artillery brigade
Brigade
A brigade is a major tactical military formation that is typically composed of two to five battalions, plus supporting elements depending on the era and nationality of a given army and could be perceived as an enlarged/reinforced regiment...
with 36 ML-20s.
The ML-20 also used by artillery regiments (24 pieces) and brigades (36 pieces) of the Reserve of the Main Command.
It was primarily used for indirect fire against enemy personnel, fortification
Fortification
Fortifications are military constructions and buildings designed for defence in warfare and military bases. Humans have constructed defensive works for many thousands of years, in a variety of increasingly complex designs...
s and key objects in the near rear. Heavy fragments of the OF-540 HE-Fragmentation shell were capable of piercing armour up to 20–30 mm thick, making a barrage dangerous to thinly armored vehicles and to some extent to heavier armoured ones as the fragments could damage chassis, sights or other elements; sometimes a close expolsion caused damage inside a vehicle even though the armour remained intact. Direct hit of a shell often resulted in tearing away a turret of a medium tank or jamming it in case of a heavy tank.
The gun was also equipped with armour-piercing shells for direct fire against armoured targets. Although not an ideal anti-tank gun because of its large size, slow traverse and slow rate of fire, in 1943 the ML-20 was one of a few guns effective against new German
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...
tanks. For example, the glacis armour of the heavy Tiger I
Tiger I
Tiger I is the common name of a German heavy tank developed in 1942 and used in World War II. The final official German designation was Panzerkampfwagen Tiger Ausf. E, often shortened to Tiger. It was an answer to the unexpectedly formidable Soviet armour encountered in the initial months of...
could be penetrated from about a kilometer.
The first combat use of the ML-20 was in the Battle of Khalkhin Gol
Battle of Khalkhin Gol
The Battles of Khalkhyn Gol was the decisive engagement of the undeclared Soviet–Japanese Border Wars fought among the Soviet Union, Mongolia and the Empire of Japan in 1939. The conflict was named after the river Khalkhyn Gol, which passes through the battlefield...
, in limited numbers. It also saw combat in the Winter War
Winter War
The Winter War was a military conflict between the Soviet Union and Finland. It began with a Soviet offensive on 30 November 1939 – three months after the start of World War II and the Soviet invasion of Poland – and ended on 13 March 1940 with the Moscow Peace Treaty...
against the Mannerheim Line
Mannerheim Line
The Mannerheim Line was a defensive fortification line on the Karelian Isthmus built by Finland against the Soviet Union. During the Winter War it became known as the Mannerheim Line, after Field Marshal Baron Carl Gustaf Emil Mannerheim. The line was constructed in two phases: 1920–1924 and...
fortifications. The gun proceeded to be used throughout the second world war.
Excellent characteristics of the gun, including reliability and ease of maintenance, allowed it to remain in service with the Soviet Army for a long time after the war.
Other operators
In the early stage of the German invasion of the Soviet Union hundreds of ML-20 were captured by WehrmachtWehrmacht
The Wehrmacht – from , to defend and , the might/power) were the unified armed forces of Nazi Germany from 1935 to 1945. It consisted of the Heer , the Kriegsmarine and the Luftwaffe .-Origin and use of the term:...
. The gun was adopted by Germans as 15.2 cm KH.433/1(r). From February 1943 Germans manufactured an ammunition for the gun.
The Finnish Army
Finnish Army
The Finnish Army is the land forces branch of the Finnish Defence Forces.Today's Army is divided into six branches: the infantry , field artillery, anti-aircraft artillery, engineers, signals, and materiel troops.-History of the Finnish Army:Between 1809 and 1917 Finland was an autonomous part of...
captured 37 guns of the type in 1941-44 and received additional 27 from Germany. These guns were adopted as 152 H 37. A number of barrels were mated with carriages of A-19 to create 152 H 37-31. While the gun was generally liked, the Finnish Army didn't possess enough prime movers suitable for towing such a massive piece. As a result, some of the guns were assigned to coastal artillery
Coastal artillery
Coastal artillery is the branch of armed forces concerned with operating anti-ship artillery or fixed gun batteries in coastal fortifications....
. Two pieces were captured back by the Red Army. A number of these guns were modernized in 1988 and as of 2004 still remain in reserve as 152 H 88-37. (all of the 152 H 88
152 H 88
152 H 88 is the name of a series of modernized 152 mm towed heavy howitzers with 32 caliber barrels. The guns of the series share the same barrel as well as other similar qualities, but differ slightly in appearance, since they consist of three different, older versions. The modernization...
series are being withdrawn as of 2007).
After the war the ML-20 was widely exported to Warsaw Pact
Warsaw Pact
The Warsaw Treaty Organization of Friendship, Cooperation, and Mutual Assistance , or more commonly referred to as the Warsaw Pact, was a mutual defense treaty subscribed to by eight communist states in Eastern Europe...
allies and to many states in Asia and Africa (in some of those states the gun still remains in service). It was adopted by Egypt
Egypt
Egypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...
and Syria
Syria
Syria , officially the Syrian Arab Republic , is a country in Western Asia, bordering Lebanon and the Mediterranean Sea to the West, Turkey to the north, Iraq to the east, Jordan to the south, and Israel to the southwest....
and therefore saw action in Arab-Israeli conflict. In 2002 a TV documentary featured ML-20 employed by the Afghan Northern Alliance forces against the Taliban fighters; it seems likely that the guns were initially supplied to the Najibullah
Mohammad Najibullah
Mohammad Najibullah Ahmadzai , originally merely Najibullah, was the fourth and last President of the Soviet-backed Democratic Republic of Afghanistan. He is also considered the second President of the Republic of Afghanistan.-Early years:Najibullah was born in August 1947 to the Ahmadzai...
's regime.
Variants
The barrel was manufactured in two variants - monobloc or built-up. Some sources indicate that a third type - with loose liner - also existed.Except the basic variant, the only variant to reach mass production was the ML-20S, developed for use in self-propelled guns, with differently placed controls for easier operation in small enclosed compartment.
- ML-20 with bag loading - In 1937 the Main Artillery Department decided - for economic reasons - to modify medium caliber guns to use bag loading instead of cased loading. An experimental ML-20 piece was built in 1939; the trials were unsuccessful.
- ML-20SM - Modified ML-20S with identical ballistics. Muzzle brake was removed. The gun was mounted in the experimental ISU-152 model 1945, of which only one unit was built.
- BL-20 - ML-20 with cast breech and wedge breechblock. Was developed by OKB-172 (sharashkaSharashkaSharashka was an informal name for secret research and development laboratories in the Soviet Gulag labor camp system...
of the NKVDNKVDThe People's Commissariat for Internal Affairs was the public and secret police organization of the Soviet Union that directly executed the rule of power of the Soviets, including political repression, during the era of Joseph Stalin....
) in 1946. - ML-20 with M-46-type carriage - ML-20 with a modified carriage, resembling in construction a carriage of the M-46 130 mm gun130 mm towed field gun M1954 (M-46)The 130 mm towed field gun M-46 M1954 is a manually loaded, towed 130 mm artillery piece, manufactured in the Soviet Union in the 1950s. It was first observed by the west in 1954...
. In 1950 an experimental piece was built and tested. - 152 H 88-37152 H 88152 H 88 is the name of a series of modernized 152 mm towed heavy howitzers with 32 caliber barrels. The guns of the series share the same barrel as well as other similar qualities, but differ slightly in appearance, since they consist of three different, older versions. The modernization...
- A Finnish modernization program - 152 mm haubico-armata wz. 37/85 - A Polish modernization, tires from KrAZKrAZKrAZ is a factory that produces trucks and other special-purpose vehicles in Kremenchuk, Ukraine; particularly heavy-duty off-road models...
255B truck, new compressed air cylinder and automotive lightingAutomotive lightingThe lighting system of a motor vehicle consists of lighting and signalling devices mounted or integrated to the front, sides, rear, and in some cases the top of the motor vehicle...
increased the road speed of the towed gun from 20 to 50 km/h and allowed the gun to be towed on public roads.
Self-propelled mounts
- SU-152SU-152The SU-152 was a Soviet heavy self-propelled heavy howitzer used during World War II.It mounted a 152 mm gun-howitzer on the chassis of a KV-1S heavy tank. Later production used IS tank chassis and was re-designated as ISU-152...
- KV-1sKliment Voroshilov tankThe Kliment Voroshilov tanks were a series of Soviet heavy tanks, named after the Soviet defense commissar and politician Kliment Voroshilov. The KV series were known for their extremely heavy armour protection during the early war, especially during the first year of the invasion of the Soviet...
heavy tank chassis, in production from February to December 1943, 670 units built. - ISU-152ISU-152ISU-152 was a Soviet multirole fully enclosed and armored self-propelled gun developed and used during World War II, with a subsequent use, mainly in the Soviet military, till the 1970s.-History:...
- IS-1Iosif Stalin tankThe Iosif Stalin tank , was a heavy tank developed by the Soviet Union during World War II and first used in the Kursk area in September 1943...
heavy tank chassis, in production from November 1943 to 1946, 3,242 units built.- ISU-152 model 1945 - a single prototype utilizing IS-3Iosif Stalin tankThe Iosif Stalin tank , was a heavy tank developed by the Soviet Union during World War II and first used in the Kursk area in September 1943...
heavy tank chassis.
- ISU-152 model 1945 - a single prototype utilizing IS-3
Summary
The ML-20 was one of the most successful Soviet artillery pieces of World War II. Its characteristics positioned it between classical short-range howitzers and special long-range guns. Compared to the former, the ML-20 has better range (e.g. the German 15 cm sFH 1815 cm sFH 18
The 15 cm schwere Feldhaubitze 18 or sFH 18 , nicknamed Immergrün , was the basic German division-level heavy howitzer during the Second World War, serving alongside the smaller but more numerous 10.5 cm leFH 18...
had range of 13.3 km), which often allowed it to shell positions of enemy artillery while remaining immune to enemy fire. Its advantage over the latter was in weight and cost, and therefore in mobility and production rate. For example, the German 15 cm K 18 with range of 24.8 km weighed 12.5 tons and only 101 pieces were built; of the excellent 17 cm K 18 (23.4 t, 29.6 km) 338 pieces were manufactured; lighter 10.5 cm sK 18 (5.6 t, 19.1 km) was more common (2,135 pieces) but its 15 kg shell was much less powerful than a 44 kg shell of ML-20. German attempts to produce an analogue to the ML-20 were unsuccessful. The 15 cm sFH 40 was never produced due to construction defects; the 15 сm sFH 42 had insufficient range and only 46 pieces were built. In 1943 and 1944 Wehrmacht announced requirements for a 15 cm howitzer with a range of 18 km, but none reached production.
Of other guns with more or less similar characteristics, there were French
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
155 mm guns model 1917 and 1918
Canon de 155mm GPF
The Canon de 155 Grande Puissance Filloux mle.1917 was a 155 mm cannon used by the French Army during the first half of the 20th century.-History:The gun was designed during World War I by Colonel L.J.F...
with longer range, but some 3.5 tons heavier (as was the US 155 mm M1 howitzer
155 mm Long Tom
The 155 mm Gun M1 and M2 , widely known as Long Tom, were 155 millimeter calibre field guns used by the United States armed forces during World War II and Korean War. The Long Tom replaced the Canon de 155 mm GPF in United States service.-Development:Before entering World War I, the United...
). The Czechoslovakian howitzer K4
Skoda K-series
The Škoda 149 mm K-series was a heavy howitzer design which served with Germany, Turkey, Romania, Slovakia, and Yugoslavia during World War II.-Description:...
(used by Germans as 15 cm sFH 37(t)) was about 2 tons lighter, but with range more than 2 km shorter and only 178 pieces were built. The British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
BL 5.5 inch (140 mm) gun
BL 5.5 inch Medium Gun
The BL 5.5 inch Gun was a British artillery gun introduced during the middle of the Second World War to equip medium batteries.-History:In January 1939 a specification was issued for a gun to replace the 6 inch 26 cwt howitzers in use with most medium batteries...
also had shorter range.
The main shortcomings of the ML-20 were its weight and limited mobility. As the experience of the ML-15 project suggests, the gun could be made somewhat lighter and more suitable for high-speed transportation. The use of a muzzle brake can be seen as a minor flaw: while softening the recoil and thus allowing the use of a lighter carriage, a muzzle brake has the disadvantage of redirecting some of the gases that escape the barrel toward the ground, where they can raise dust, potentially revealing the gun position. But when the ML-20 was developed, muzzle brakes were already a common design element in artillery pieces of that class.
Ammunition
| Available ammunition | |||||
| Type | Model | Weight, kg | HE weight, kg | Muzzle velocity, m/s | Range, m |
| Armor piercing shells | |||||
| APHE | BR-540 | 48.8 | 0.66 | 600 | 4,000 |
| APBC (from late 1944) | BR-540B | 46.5 | 0.48 | 600 | 4,000 |
| Naval semi-AP | model 1915/28 | 51.07 | 3.2 | 573 | |
| HEAT | BP-540 | 27.44 | 680 | 3,000 | |
| Anti-concrete shells | |||||
| Anti-concrete howitzer shell | G-530 / G-530Sh | 40.0 | 5.1 | ||
| Anti-concrete gun shell | G-545 | 56.0 | 4.2 | ||
| High explosive and fragmentation shells | |||||
| Gun shells | |||||
| HE-Fragmentation, steel | OF-540 | 43.6 | 5.9-6.25 | 655 | 17,230 |
| HE-Fragmentation, steel | OF-540Zh | 43.6 | 5.9-6.25 | ||
| HE, old | F-542 | 38.1 | 5.86 | ||
| HE, old | F-542G | 38.52 | 5.83 | ||
| HE, old | F-542ShG | 41.0 | 5.93 | ||
| HE, old | F-542Sh | 40.6 | 6.06 | ||
| HE, old | F-542ShU | 40.86 | 5.96 | ||
| HE, old | F-542U | 38.36 | 5.77 | ||
| Howitzer shells | |||||
| HE-Fragmentation, steel | OF-530 | 40.0 | 5.47-6.86 | ||
| HE-Fragmentation, steely iron | OF-530A | 40.0 | 5.66 | ||
| HE, old | F-533 | 40.41 | 8.0 | ||
| HE, old | F-533K | 40.68 | 7.3 | ||
| HE, old | F-533N | 41.0 | 7.3 | ||
| HE, old | F-533U | 40.8 | 8.8 | ||
| HE, steely iron, old French | F-534F | 41.1 | 3.9 | ||
| HE for 152-mm mortar model 1931 | F-521 | 41.7 | 7.7 | ||
| HE, British, for Vickers 152-mm howitzer | F-531 | 44.91 | 5.7 | ||
| Shrapnel shells | |||||
| Shrapnel with 45 sec. tube | Sh-501 | 41.16-41.83 | 0.5 (680—690 bullets) | ||
| Shrapnel with Т-6 tube | Sh-501T | 41.16 | 0.5 (680—690 bullets) | ||
| Illumination shells | |||||
| Illumination, 40 sec. | S 1 | 40.2 | |||
| Chemical shells | |||||
| Fragmentation-chemical gun shell | OH-540 | ||||
| Chemical howitzer shell | HS-530 | 38.8 | |||
| Chemical howitzer shell | HN-530 | 39.1 | |||
| Chemical (post-war) | ZHZ | ||||
| Armour penetration table | ||
| APHE shell BR-540 | ||
| Distance, m | Meet angle 60°, mm | Meet angle 90°, mm |
| 500 | 105 | 125 |
| 1000 | 95 | 115 |
| 1500 | 85 | 105 |
| 2000 | 75 | 90 |
| APBC shell BR-540B | ||
| Distance, m | Meet angle 60°, mm | Meet angle 90°, mm |
| 500 | 105 | 130 |
| 1000 | 100 | 120 |
| 1500 | 95 | 115 |
| 2000 | 85 | 105 |
| Naval semi-AP model 1915/28 | ||
| Distance, m | Meet angle 60°, mm | Meet angle 90°, mm |
| 100 | 110 | 136 |
| 500 | 104 | 128 |
| 1000 | 97 | 119 |
| 1500 | 91 | 111 |
| 2000 | 85 | 105 |
| These data was obtained by Soviet methodics of armour penetration measurement (penetration probability equals 75%). They are not directly comparable with western data of similar type |
||
Interesting facts about ML-20
- On 2 August 1944 the ML-20 howitzer-gun No. 3922 became the first gun to shell German territory in the second half of World War II.
- Loader of the ML-20 had to carry 40 kg shells alone.
- The 41st artillery brigade - one of the first brigades to be equipped with the ML-20 - after a number of reorganizations became a training center for soldiers and sergeants of the Russian Army Missile and Artillery Forces. There is a memorial ML-20 piece in one of the center's parks.
- A small number of operational ML-20 howitzer-guns is still present in the Russian Army ordnance depots.
- 152 mm HE-Frag projectiles OF-540, initially developed for the ML-20, are still in Russian Army service and can be fired from modern 152 mm ordnance pieces.
- ML-20 howitzer-guns were towed by heavy artillery tractors Voroshilovetz and Komintern; these vehicles produced by the same KharkovKharkivKharkiv or Kharkov is the second-largest city in Ukraine.The city was founded in 1654 and was a major centre of Ukrainian culture in the Russian Empire. Kharkiv became the first city in Ukraine where the Ukrainian Soviet Socialist Republic was proclaimed in December 1917 and Soviet government was...
locomotive plant that developed the T-34T-34The T-34 was a Soviet medium tank produced from 1940 to 1958. Although its armour and armament were surpassed by later tanks of the era, it has been often credited as the most effective, efficient and influential design of World War II...
tank and were equipped with the same V-2 diesel engineDiesel engineA diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...
.
Surviving pieces
- In the Central Armed Forces MuseumCentral Armed Forces MuseumThe Central Armed Forces Museum also known as the Museum of the Soviet Army, is located in northern Moscow near the Red Army Theater.-History:...
and at the Poklonnaya HillPoklonnaya HillPoklonnaya Gora is, at 171.5 metres, one of the highest spots in Moscow. Its two summits used to be separated by the Setun River, until one of the summits was razed in 1987...
, MoscowMoscowMoscow is the capital, the most populous city, and the most populous federal subject of Russia. The city is a major political, economic, cultural, scientific, religious, financial, educational, and transportation centre of Russia and the continent...
, RussiaRussiaRussia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
. - In the Museum of Artillery and Engineering Forces, Saint PetersburgSaint PetersburgSaint Petersburg is a city and a federal subject of Russia located on the Neva River at the head of the Gulf of Finland on the Baltic Sea...
, Russia. - In The Artillery Museum of FinlandThe Artillery Museum of FinlandThe Artillery Museum of Finland is a special military museum dedicated to the history of the artillery from the 15th century to the present day. It was located in Niinisalo from 1977 to 1997...
, HämeenlinnaHämeenlinnaHämeenlinna is a city and municipality of about inhabitants in the heart of the historical province of Häme in the south of Finland and is the birthplace of composer Jean Sibelius. Today, it belongs to the region of Tavastia Proper, and until 2010 it was the residence city for the Governor of the...
, FinlandFinlandFinland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...
. - In the IDF History Museum (Batey ha-Osef), Tel AvivTel AvivTel Aviv , officially Tel Aviv-Yafo , is the second most populous city in Israel, with a population of 404,400 on a land area of . The city is located on the Israeli Mediterranean coastline in west-central Israel. It is the largest and most populous city in the metropolitan area of Gush Dan, with...
, IsraelIsraelThe State of Israel is a parliamentary republic located in the Middle East, along the eastern shore of the Mediterranean Sea...
. - In PoznańPoznanPoznań is a city on the Warta river in west-central Poland, with a population of 556,022 in June 2009. It is among the oldest cities in Poland, and was one of the most important centres in the early Polish state, whose first rulers were buried at Poznań's cathedral. It is sometimes claimed to be...
Citadel, PolandPolandPoland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...
. - In the Lubuskie Military Museum, Drzonów, PolandPolandPoland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...
. - In the US Army Ordnance MuseumUnited States Army Ordnance MuseumThe U.S. Army Ordnance Museum is a museum that is in the process of being re-located to Fort Lee, in Fort Lee, Virginia. Its previous building—at Aberdeen Proving Ground in Aberdeen, Maryland—was closed in September 2010, although many outdoor exhibits are still accessible to the...
, AberdeenAberdeen, MarylandAs of the census of 2000, there were 13,842 people, 5,475 households, and 3,712 families residing in the city. The population density was 2,166.2 people per square mile . There were 5,894 housing units at an average density of 922.4 per square mile...
, MarylandMarylandMaryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...
, USA.