122 mm corps gun M1931/37 (A-19) () was a Soviet field gun developed in late 1930s by combining the barrel of the 122 mm gun M1931 (A-19) and the carriage of the 152 mm howitzer-gun M1937 (ML-20). The gun was in production from 1939 until 1946. It saw action in World War II (primarily with corps and RVGK artillery of the Red Army) and remained in service for a long time after the end of the war. Vehicle-mounted variants of the gun were fitted to the IS-2 and IS-3 tanks of the Iosif Stalin series of tanks and the ISU-122 self-propelled gun.
Development history
In 1936 the Red Army adopted the 122 mm gun M1931, also known as A-19. Unlike earlier ordnance pieces used by the Red Army, it had split trail carriage with suspension, and consequently improved mobility and traverse. The carriage of M1931 had a number of shortcomings though. The elevation mechanism was slow and unreliable; solid-tired wheels hindered mobility to some extent; there were technological problems in carriage production.
Soon after the M1931, the Red Army received another artillery piece in form of the 152 mm howitzer-gun M1937 (ML-20), developed at the No. 172 Plant, under F. F. Petrov. This led to an upgrade of the M1931, handled also by Petrov's design bureau. The barrel of the M1931 was placed on the carriage of a ML-20. The improved gun successfully underwent trials in September–October 1938 and on 29 April 1939 was adopted as 122 mm corps gun M1931/37. Unusually, the new variant, like the old one, was referred to as A-19.
Production history
The M1931/37 was manufactured by the Barrikady Plant in Stalingrad (1939–41), No. 172 Plant (1941–46). The number of M1931/37s manufactured can be estimated at about 2,450, not including those mounted on vehicles.
Description
Like barrel of late production M1931, the barrel of the M1931/37 was of loose liner construction, and consisted of liner, jacket and screwed-upon breech. The breechblock was of interrupted screw type, similar in construction to that of the 152 mm howitzer M1910/37. Recoil system consisted of hydraulic recoil buffer and hydro-pneumatic recuperator, both located inside the cradle under the barrel.
The gun had split trail carriage adapted from the 152 mm howitzer-gun M1937 (ML-20). The carriage was fitted with leaf spring suspension and metal wheels with pneumatic tires. The carriage also featured an equilibrator. The shield gave the crew some protection from small arms and shell fragments.
The M1931/37 was transported as a single piece, with barrel pulled back. It was permitted to tow the gun with barrel in its normal position, but for short distances only and with speed of no more than 4–5 km/h. Several types of artillery tractors were used: S-2 Stalinets-2, Komintern and, from 1943, Ya-12.
Organization and employment
Both variants, M1931 and M1931/37, had the same place in army organizations, were often used alongside each other and combat reports rarely differentiate between them; consequently, the data in this section is for M1931 and M1931/37 together, unless specified otherwise.
Red Army
The A-19 was originally intended for corps artillery. Together with ML-20 it formed a so-called "corps duplex". In 1940–41 there were three types of corps artillery regiments: With two battalions 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 the Great Patriotic War the corps artillery was eliminated (as rifle corps themselves were eliminated) and was only reintroduced late in the war. Those new artillery regiments were issued 122 mm guns along with other pieces, mainly 107 mm guns and 152 mm howitzers, in total 16-20 pieces per regiment. On 1 June 1944, RKKA corps artillery possessed 387 A-19s (along with some 750 107 mm and 152 mm pieces), and on 1 May 1945—289 A-19s (again along with some 750 100 mm, 107 mm and 152 mm pieces).
The gun was also used by artillery units of the Reserve of the Main Command (RVGK). In mid-1941 a cannon regiment of the RVGK had 48 A-19; in autumn 1941 these regiments were reorganized, a new, smaller, regiment had 18 A-19s. From 1942 cannon brigades were introduced, with 36 A-19s each. Such brigade could be a part of an artillery division—a huge formation, with up to four brigades of A-19 or ML-20 (meaning up to 144 pieces).
The first combat use of the A-19 was in the Battle of Khalkhin Gol. It also saw combat in the Winter War. On 1 March 1940 there were 130 A-19 guns at the frontline. Three pieces were lost.