Post World War II, the ML-20 saw combat in numerous conflicts during the mid to late twentieth century.

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.

The device, called meteoballistic summator, consisted of a specialized slide rule and a pre-calculated table.

To assist loading when the barrel was set to high elevation angle, the breech was equipped with cartridge holding mechanism.

The carriage was of split trail type, with shield and balancing mechanism, leaf spring suspension and steel wheels with rubber tires (some early production pieces received spoked wheels with solid tires from M1910/34).

172 Plant in Motovilikha tried to continue the modernization works, but the Main Artillery Directorate (GAU) insisted on more significant upgrade.

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.

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 (Russian: 152-мм гаубица-пушка образца 1937 года (МЛ-20)).

Some sources claim that the choice was made because of the economic factor—the ML-20 was more similar to the M1910/34, thus requiring fewer adjustments for production.

Second, after the Soviets started to field heavy tanks such as the JS series that used the A-19 122mm gun, the plant was ordered to increase the production of the A-19 instead of the ML-20.

It was primarily used for indirect fire against enemy personnel, fortifications and key objects in the near rear.

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.

[citation needed] In the early stage of the German invasion of the Soviet Union hundreds of ML-20 were captured by the Wehrmacht.

While the gun was generally liked, the Finnish Army didn't possess enough prime movers suitable for towing such a massive piece.

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.

In 1943 and 1944 Wehrmacht announced requirements for a 15 cm howitzer with a range of 18 km, but none reached production.

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 Italian Cannone da 149/40 modello 35 had a range of 23.7 km but had a weight of 11 tons and less than 100 pieces were built.

The British BL 5.5 inch (140 mm) Medium Gun probably had the closest characteristics; weight slightly over six tons and range of 18,100 yd (16,600 m) with an 82 lb (37 kg) shell.

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.

World War II Post-war Present Day ML-20s are on display in a number of military museums.