152-mm Howitzer-gun Ml-20,Technical Details – USSR

152-mm Howitzer-gun Ml-20 Specifications

  • Years of issue – 1937 – 1946
  • In total, produced – 6884 units.
  • Caliber – 152 mm
  • Weight in firing position – 7270 kg
  • Barrel length – 4930 mm
  • The length of the threaded part – 3467 mm
  • Calculation – 9 people
  • Travel speed – up to 25 km / h
  • Rate of fire – 3 – 4 rds / min
  • The greatest firing range – 17230 m
  • Direct shot range – 825 m
  • Shooting angles :
  • Horizontal – 58 °
  • Vertical -2 ° + 65 °

152-mm Howitzer-Gun Ml-20 Details

ML-20 – 152-mm Soviet howitzer-gun. In fact, this term was specially introduced specifically for the ML-20 in order to emphasize its unique fighting qualities. The double name – “howitzer-cannon” – means that this gun combines the qualities of both main types of artillery systems, and it was located in a niche between the classic field howitzers with a short barrel and long-range long-barreled guns of special power, greatly outperforming the former in firing range. and the latter in mass, mobility and price.In practice, the first advantage led to the ML-20 being capable of striking the positions of the most common enemy howitzers, firing from inaccessible distances. The result of the second advantage was a much larger number of ML-20 fired compared to the number of special-power guns produced, which were significantly more expensive.

Back in 1932, a group of designers of the All-Union Arsenal Arsenal – V. Grabin, N. Komarov and V. Drozdov proposed to create a powerful 152-mm corps cannon by superimposing the barrel of the 152-mm Schneider siege cannon on the carriage of the 122-mm A-19 cannon. At that time, Schneider’s 1910 siege cannon, according to its ballistic data, was one of the best weapons in the world. In 1930 and 1934, it was modernized, but many of the shortcomings in the 152-mm cannon of the 1910/34 model could not be eliminated.She had a number of disadvantages: the lack of suspension at the front end limited the speed of movement; a complex lifting and balancing mechanism provided an insufficiently high vertical aiming speed; it took a lot of energy and time to transfer the barrel from the marching position to the firing position and back; the cradle with recoil devices was difficult to manufacture. At the same time, this type of weapon was in great demand in the army.

All work on the modernization of the 1910/34 model cannon was carried out at the artillery plant No. 172 in Motovilikha. All technological equipment was prepared for it at the plant. Therefore, plant number 172 was instructed to create a new powerful weapon. Howitzer-gun, called “ML-20”, created in the factory design bureau by a group of designers led by F.F. Petrov, was designed on a proactive basis in parallel with the 152-mm howitzer-gun ML-15, for the development of which the plant had the task of GAU. Unlike the designers of the ML-15, F.F. Petrov strove in his gun to make maximum use of the best components and mechanisms of the 1910/1934 cannon, including the barrel. A new carriage was created for it, which meets all the requirements.

Despite the wide unification with the gun mod. 1910/1934, the ML-20 cannon howitzer received a number of new elements. So, a new cast upper machine was developed, the combined lifting and balancing mechanism was divided into two independent – sector lifting and balancing, new ones were designed: a front with suspension, a mechanism for changing the length of the rollback (depending on the elevation angle), a mechanism for turning on and off the springs, a sight with an independent line of sight and a cradle with a cast trunnion clip (instead of a forged one).This practically new carriage was recognized as normalized, receiving the designation 52-L-504A and, later, was used to create the 122-mm A-19 cannon of the 1931/37 model. Thus, the Perm designers managed to create, for the first time in world practice, an intermediate type weapon with the properties of both a cannon and a howitzer. The elevation angle, increased to 65 °, and 13 variable charges made it possible to obtain a gun with unique fire maneuvering capabilities, which could be used both as a howitzer, firing along a hinged trajectory with a relatively low projectile velocity, and as a cannon, along a flat trajectory with a high projectile velocity. A. Bulashev, S. Gurenko, M. Burnyshev, A. Ilyin and others took an active part in its development and creation.

When developing this weapon, special attention was paid to improving manufacturability and reducing cost. It was with the production of the ML-20 howitzer-gun in artillery technology that the widespread use of steel shaped casting began. Many assemblies – upper and lower machines, hinge and trunk parts of beds, wheel hubs – were made of cheap carbon steels. In 1936, the first prototype of the ML-20 was ready. In the course of comparative state tests ML-20 and ML-15, the winner was the Petrov’s ML-20 cannon, adopted on September 22, 1937 by the Red Army under the name “152-mm howitzer-gun of the 1937 model.”

ML-20 had a modern design for its time with a carriage with sliding beds and a sprung wheel travel. The 152-mm barrel borrowed from the 1910/1934 cannon had a powerful slit-type muzzle brake.

The barrel for the ML-20 was produced in three versions: a monoblock, a barrel with a free tube and a fastened barrel. The ML-20 was equipped with a piston bolt, a hydraulic spindle-type recoil brake, a hydropneumatic knurler and had a separate-sleeve loading. The shutter was opened and closed by turning the handle. The shot is fired by pulling the trigger by the trigger cord. For the forced ejection of the sleeve from the barrel chamber after the shot, an ejector was mounted in the slot of the breech, which acts automatically when the bolt is opened. The bolt had a safety mechanism that allows you to open the bolt (by turning the handle) only after the shot.

To prevent the sleeve and the projectile from falling out of the barrel when loading at large elevation angles, there was a sleeve retention mechanism in the upper part of the breech piston socket. The gun had a mutual closure mechanism that prevented the bolt from opening if the barrel was not properly connected to the recoil devices. The howitzer-gun carriage consisted of: a cradle with recoil devices; upper machine; aiming mechanisms (lifting and turning); balancing mechanism with flaps; lower machine with two beds and a combat move; shield cover to protect against bullets and shrapnel; sighting devices, in the form of a telescopic sight for direct fire and an artillery panorama for firing from closed positions.

Double metal wheels with rubber tires (some guns had spoked wheels and rubber weights from the 1910/34 cannon), leaf springs. The transportation of the gun was usually carried out on a gun carriage with the barrel in a retracted position. The transition time from the traveling position to the combat position was 8 – 10 minutes. For short distances, the system could be transported with an unstretched barrel at a speed of 4 – 5 km / h. The design of the sprung carriage and the presence of a sprung front end also made it possible to transport the gun with a medium artillery tracked tractor “Voroshilovets” and “Comintern” at a relatively high speed of up to 25 km / h.

The 152-mm howitzer-gun ML-20 had a huge range of ammunition, allowing it to solve a wide variety of tasks. To her ammunition included shots with shells: high-explosive fragmentation (several types); armor-piercing tracer; cumulative; concrete-piercing howitzer. The firing range of a high-explosive fragmentation projectile weighing 43.56 kg with an initial speed of 655 m / s was 17230 m. When the fuse was installed on the fragmentation action, the projectile inflicted damage with fragments along the front by 40 m and in depth up to 8 m.An armor-piercing tracer projectile, when fired with direct fire at a distance of up to 800 m, pierced the armor of all enemy tanks. A cumulative projectile pierced armor at an angle of 90 ° – 250 mm, 60 ° – 220 mm, 30 ° – 120 mm at all distances. Since the calculation of the trajectory elements and corrections for meteorological conditions for this weapon was difficult due to the large nomenclature of shells and charges, a meteorological ballistic adder was specially developed for the ML-20 – a mechanical calculating device that combines a reference table and a specialized slide rule. It allowed the artillery calculator to quickly and accurately calculate the necessary data for firing. In the post-war period, such devices were produced for all weapons accepted for service.

For the first time, the ML-20 howitzer-gun was used during the battles on the Khalkhin-Gol River, then it was actively used in the Soviet-Finnish war, where it was used to destroy pillboxes and bunkers on the Mannerheim Line. ML-20 took part in all major operations of the Great Patriotic War. The ML-20 cannon howitzer was used for firing from closed positions at sheltered and openly located enemy manpower, its fortification barriers and objects in its immediate rear.

The 152 mm howitzer-gun turned out to be a much more flexible, powerful and effective weapon than previously thought. The combat experience of the battles of the Great Patriotic War continuously expanded the range of tasks assigned to this weapon. In addition to targets such as military columns, headquarters, warehouses, artillery positions typical for such artillery systems, the ML-20 was successfully used to destroy long-term firing structures, including concrete ones, and, in some cases, with direct fire. Their use in urban battles was very effective.It should be noted that the ML-20 was used for anti-tank purposes, which was the most extreme measure, since for such purposes the ML-20 is too large (accordingly, it is easily detected and struck), high cost and low aiming speed. At the same time, in a number of cases, for example, in the Battle of Kursk, with the ineffectiveness of standard anti-tank weapons against new enemy tanks, the ML-20 was involved in anti-tank warfare.Armor-piercing and concrete-piercing shells ML-20 easily hit all medium tanks of the Wehrmacht when firing in any projection, “Tiger” and “Ferdinand” were also struck when firing at ranges of about 1 km or less in all projections, and when firing at the side and at more distant distances. Tank “Panther” was hit in the side at all distances, including close – in the frontal armor. When a high-explosive fragmentation projectile hit the tank, the turret was tore off the medium tanks; in heavy tanks, it was jammed from concussion (and there was a significant probability of destruction of structural elements of the shoulder strap and displacement of the tower from the axis of rotation), weapons, observation devices failed, and the crew was injured.

In the late 1930s, the 152-mm howitzer-gun ML-20, together with the 122-mm cannon A-19, made up the so-called “corps duplex” – two guns that entered service with the corps artillery regiments (24 or 36 howitzer guns ML-20).

Since 1943, the ML-20 was used in the artillery regiments of the combined-arms armies (18 ML-20 each). From the beginning of 1945, the Guards armies had an artillery brigade (36 ML-20). In addition, the ML-20 was in service with the artillery brigades and regiments of the RVGK (24 ML-20 each). Since 1943, artillery brigades of the RVGK (36 ML-20) have been formed. The ML-20 cannon howitzer was a successful weapon of the Soviet army, serving until the 1970s.

The ML-20 cannon howitzer was mass-produced at the factory # 172 (Perm) from 1937 to 1946. A total of 6,884 ML-20 howitzer-guns were manufactured, along with them, about 4,000 ML-20S barrels were fired for installation on the most powerful Soviet self-propelled artillery mounts of the Great Patriotic War – SU-152 and
ISU-152.

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