| 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 to standardize the artillery used by the Red Army. Letter № 51225/12YA5 on March 22, 1927 A. K. ordered C. B. "Artkoma" to make the following modernization projects, a 122-mm gun cabinet, 152-mm gun ARGK, and 203-mm howitzer ARGK. The Artillery Design Bureau under F. F. Lender in January of 1926 was tasked to develop the project "203-mm howitzer, great distance." After the death of F. F. Lender the project was transferred to the KB "Bolshevik" plant. On December the 11th, 1926 at a meeting, Artkoma made a decision: " The project was completed on the 16th January, 1928 in two versions:one with and one without a muzzle brake. Preference was then given to the design without a muzzle brake, as studies found that the muzzle break was not needed. The production of the swinging howitzers (gun barrel and gun components) was carried out at the KB "Artkoma" plant, and the motorised carriage and tracks at KB "Bolshevik" plant. The first prototype 203-mm howitzer B-4 was completed at the KB "Bolshevik" plant at the beginning of 1931. Testing was then conducted from July and August by the NIAP to test ammunition charges for the B-4. After military trials the howitzer was adopted in 1933 by the Red Army as "203-mm howitzer B-4 arr. 1931"