122 Mm Howitzer M1938 (M-30) - Development

Development

In 1930 Red Army (RKKA) authorities started to look for a new divisional-level howitzer to replace the pre-World War I 122-mm howitzer M1909 and 122-mm howitzer M1910. Although both pieces were eventually modernized, resulting in the 122-mm howitzer M1909/37 and the 122-mm howitzer M1910/30 respectively, these upgrades did not address some shortcomings in the original designs.

The first attempt to develop a new howitzer was made by the KB-2 design bureau under the supervision of German engineers. The design, known as Lubok, reached trials in 1932 and in 1934 was adopted as the 122-mm howitzer model 1934. It had a 23 caliber barrel, a maximum elevation of 50°, traverse of 7°, and a combat and travelling weight of 2,250 and 2,800 kg respectively. Like its predecessors, Lubok had a fixed trail carriage and although it was equipped with suspension, its wheels lacked tires, limiting towing speed to only 10 km/h. Nevertheless, it was undoubtfully superior to the M1910/30 which remained in production until 1941. However, after eight pieces were built in 1934-1935, production was stopped for unclear reasons, possibly relating to the disbanding of KB-2.

In the mid-1930s, the Main Artillery Directorate (GAU) considered a switch to 105 mm guns as used by some other armies. A smaller shell meant that the gun could be lighter and consequently more mobile. On the other hand a 105 mm gun would also be less powerful. Moreover, there was no Russian or Soviet experience with 105 mm ammunition, while for the 122 mm the country already possessed both production lines and large numbers of already manufactured shells (however similar 107 mm manufacturing equipment and ammunition — for the 107-mm gun M1910 — was available). Finally in 1937 the RKKA Head of General Staff I. I. Egorov supported retaining 122 mm ammunition.

Consequently three howitzers were trialled in 1938–1939. The design bureau of UZTM (Ural Heavy Machinery Plant, Russian: Уральский Завод Тяжёлого Машиностроения, УЗТМ), which was ordered by GAU to design the new howitzer, developed a piece designated U-2. Similar projects were privately undertaken by the design bureaus of Motovilikha Plants, headed by F. F. Petrov (M-30), and by the No. 92 plant under V. G. Grabin (F-25).

The U-2 (barrel length 21 calibers, chamber volume 3.0 litres, horizontal sliding breechblock from Lubok, muzzle brake, combat weight 2,030 kg) reached trials on 5 February 1939 and was rejected because of insufficient carriage strength and inferior ballistics. The F-25 project (barrel length 23 calibers, chamber volume 3.7 litres, horizontal sliding breechblock from Lubok, muzzle brake, combat weight 1,830 kg) was closed by GAU on 23 March 1939 as GAU considered it redundant to the M-30 which had reached trials earlier. The latter, after being returned several times for revision, was finally adopted in September 1939 as the 122 mm divisional howitzer M1938 (Russian: 122-мм гаубица образца 1938 года (М-30)). Its GAU index number was 52-G-463.