| 203 mm howitzer M1931 (B-4)|
203-мм гаубица обр. 1931 г. (Б-4)
That's what we call a "door-knocker"
The Soviet B-4 203mm heavy howitzer are specialized in blasting enemy heavy fortifications or urban areas. Very heavy, it was best used as fixed or siege artillery that provided fire support at very long range. Its high-angled 100 kg shells can easily blast any building or grouping of light troops, even unidentified, in just a few shots. However the 203mm is imprecise at long range, and extremely slow, despite the fact it is self-propelled for local maneuvering thanks to an engine in that tracked chassis.
By itself, a single Gaubitsa unit is practically worthless, hitting wide of the mark, and taking quite a while to reload between shots. It's too inaccurate to do much damage despite its strength; however grouped together in units of 4+, and with the right target, Gaubitsas can destroy entire enemy bases, totally crippling and destroying war efforts in one well aimed volley.
This section was directly translated off of the Russian Wikipedia. Just wondering if someone can improve the language mistakes.
In November 1920, at the Artillery Committee (Artkome), which was headed by R. A. Durlyahov, was created. Artillery Design Bureau under the direction of F. F. Lender . He was, in January 1926 tasked to develop the project "203-mm howitzer great distance." After the death of F. F. Lender the project was transferred to the plant "Bolshevik" . On December the 11th, 1926 at a meeting, Artkoma made a decision: "To instruct C. B. Artkoma to develop project 203-mm howitzer great distance in 46 month" Letter № 51225/12YA5 on March 22, 1927 A. K. ordered C. B. "Artkoma" to make common projects 122 - mm gun cabinet, 203-mm howitzers ARGK and 152-mm guns ARGK. The howitzers project was completed on the 16th January, 1928 in two versions: with and without muzzle braker. Body of guns and ballistics in both versions were identical. Preference was given to the trunk without a muzzle braker. Detailed drawings of the swinging howitzers were developed KB "Artkoma" and working drawings of the machine gun carriage on tracks KB factory "Bolshevik." The first prototype 203-mm howitzer B-4 was produced at the plant "Bolshevik" at the beginning of 1931 in July and August 1931 conducted by NIAP Shooting for the purpose of selection of the charges to the B-4. After a long and ground military trials in the 1933 howitzer was adopted by the Red Army under the designation of 203-mm howitzer arr. 1931