A 152 mm caliber gun, model 37, known as the ML-20 and indexed 52-G-544A - a domestic howitzer-gun used during WW2. G-P was mass produced from 37 to 46. Used (and is used) by many countries of the world. It has been used in almost all military conflicts since the middle of the 20th century. Some of the most powerful Russian self-propelled guns 2МВ ISU-152 and SU-152 were equipped with these howitzers. Of the guns that have entered service, the ML-20 is one of the best design solutions for barreled guns to this day. ML-20 played a huge role in the development and modernization of domestic artillery installations in the second half of the 20th century.
Creation of ML-20
By the 1930s, only a siege weapon of the 1910 model was in service with the Red Army from the corps link of artillery guns. The gun was created by the French company "Schneider" for the Russian armed forces. It was actively used in the First World War and in other military conflicts. By 1930, this weapon was already morally obsolete, but it is still being modernized. Combat characteristics increased, but the mobility, angle and speed of aiming left much to be desired. The last time they tried to modernize it was in 35-36 at plant number 172, but the main artillery department did not support this direction of work. The designers of the plant begin to develop a new weapon.
Factory designers have created two guns ML-20 and ML-15. The ML-15 was created by order of the main artillery department. ML-20 - the designers' own initiative. They inherited from the obsolete gun - the barrel, the bolt, the anti-rollback devices. In mid-36, the ML-15 was sent to a training ground for testing. The tests were found unsuccessful, and the gun was sent for revision. The beginning of the 37th year - repeated tests of the modified ML-15, the tests are recognized as successful. The ML-20 gun was sent for testing at the end of the 36th year, in the 37th year, military trials are being successfully carried out. It was after these tests, with minor modifications, that the ML-20 was recommended for use in the armed forces. End of September '37 - ML-20 officially, as a 152-mm howitzer-gun model '37, is accepted into service in the Soviet army. The ambiguous choice of GP ML-20 instead of GP ML-15 is little-explained today. The ML-15 was clearly lighter than the ML-20, it had a rather high transport speed at that time - up to 45 km / h. The modern and sophisticated design of the carriage part is definitely not among the disadvantages of the ML-15. By the way, after a while, the GP ML-20 was modernized, and the carriage resembled the design of the ML-15. Some sources report that the choice was made due to the financial side of the issue - the production of the ML-20 was cheaper than the ML-15.
Airframe ML-20
As the name suggests, the ML-20 is an artillery system with a predominance of howitzer properties. It had a design with a carriage and sliding beds. The barrel had two versions - monoblock and fastened. Other equipment: piston valve, hydraulic retractable spindle brake, hydropneumatic knurler. The charge of the Г-П is separate. The bolt is equipped with a mechanism for forced ejection of the sleeve when opening after firing a shot, and a fuse that locks the bolt after separate loading, but before the shot is fired. If necessary, when it is necessary to discharge the howitzer-gun, the fuse is switched to open the bolt. Case retention mechanism, helps to load at high angles. Shooting is carried out with the help of the trigger cord, which, when pulled, pulls the trigger. The GP ML-20 is equipped with a mutual closure mechanism, it did not allow the gun bolt to open if the anti-rollback devices were not connected to the barrel in the correct way. Muzzle brake with slotted holes, softened the recoil on anti-rollbacks with a gun carriage. The recoil device with a knurled roller was provided with 22 liters of special fluid, the pressure in them was equal to 45 atmospheres.
A distinctive feature of the GP ML-20 is a set of initial velocities and elevation angles, which are set by one of a dozen shells. The result of such a set is a howitzer for ammunition with a hinged trajectory, a cannon for ammunition with a flat trajectory. ML-20 was equipped with a telescopic sight for firing a direct fire, and a panorama for firing a shot along a hinged trajectory. Due to the fact that the ammunition used turned out to be quite a lot, the calculation of various corrections and trajectories for each of them separately would take a fairly long period of time - a meteorological ballistic adder is created for them. This solution is a combination of a logarithmic ruler and a look-up table. With its use, the time for calculating the trajectory and meteorological data for shooting has been significantly reduced. The successful use of the adder during WW2 showed its high efficiency. After WW2, the adder was produced with all new types of guns. The carriage, which has a sliding type bed, was equipped with a balancing mechanism and a shield-like cover. The metal wheels had rubber tires and leaf springs. The movement of the GP ML-20 was carried out with the trunk retracted. The transition for combat use took an average of 9 minutes. Travel speed in the field is 5-8 km / h. The carriage was named "52-L-504A", and was also used to modify the 122 mm gun A-19.
Application of ML-20
Basically, the ML-20 was used as a weapon of closed positions, and was used to defeat and destroy open and sheltered enemy manpower, fortifications and barriers, objects located on the front line of the front. The HE-540 high-explosive fragmentation grenade detonator, exposed to fragmentation action, gave a grenade weighing 43.5 kilograms, the following striking characteristics: 8 meters deep and 40 meters wide from the crash site. Fewer fragments compared to a howitzer grenade ensured armor-piercing up to 3 centimeters. Fire with such grenades made it possible to defeat not only personnel, but also armored vehicles of the enemy. All armored vehicles up to and including medium tanks were defeated. Technicians with heavy armor, grenades disabled the chassis, guns and sights.
The first use in combat was the battles on Khalkin Gol. It was used to destroy and defeat the fortified structures of the Mannerheim Line. It was used in World War II, and played a noticeable role in the Kursk Bulge as an effective means of fighting the latest enemy tanks and armored vehicles. After the Victory, a well-proven weapon was supplied to friendly countries, was used for a long time in its own armed forces, and took part in many major military conflicts of the second half of the 20th century. Some countries in Africa and Asia still use the ML-20 in the armed forces.
ML-20 on self-propelled units:
- WW2 self-propelled gun - SU-152. Base from the KV-1s tank. Serially produced in '43. Quantity - 670 units;
- self-propelled artillery unit - ISU-152. Base from the IS-1 tank. Serially produced from 43 to 46. Quantity - 3242 units;
- self-propelled artillery unit - ISU-152, issue 45. Base from the IS-3 tank. Not serially produced Quantity - 1 prototype.
