These guns were used with success against Finnish pillboxes at the Mannerheim Line, heavy German fortifications and in urban combat for destroying protected buildings and bunkers.

These guns were used until the end of the war in the Battle of Berlin, during which the Red Army used them to smash German fortifications at point blank range with their heavy 203mm shells.

The heavy recoil from the muzzle blast threw the crew off their seats and damaged the transmission, and so it was cancelled.

[3] With an elevation angle of up to 60 degrees and 12 propellant loads to choose from, the B-4 virtually met all the expectations it was given, capable of crushing its targets via an optimal projectile trajectory.

Preference was eventually given to the brake-free variant with technical drawings by the Artkom design bureau, and a tracked carriage (a common sight on heavy Soviet artillery pieces) from the Bolshevik plant.

As a result, despite bearing the common designation of B-4, there were virtually two different models of the howitzers in practical service.

Drawings were not unified until 1937, when individual parts and assembly designs, then already tested both in production and in trials, had their layouts changed.

The only innovation was the tracked carriage, which allowed firing outright from the ground without any kind of special platforms, unlike many similar weapons.

The B-4 was also called the "Karelia Sculptor" as Finnish pillboxes hit were virtually turned into a hodge-podge of concrete chunks and iron armatures.

After the start of the Great Patriotic War, the Howitzer Regiments were evacuated to the far rear for protection, only returning on November 19, 1942 when the strategic initiative was wrestled back into Soviet hands.

Captured B-4's used by the Wehrmacht were given the designation 20.3 cm Haubitze 503/5(R),[5] of which 8 pieces remained at the Eastern Front by March 1944, firing a mix of G-620 concrete-buster and German shells.