Soviet 203mm B-4M howitzer on display in firing configuration with wheels raised off the ground.
Source: One half 3544 -
© Public domain
The B-4M is an early Cold War era heavy towed howitzer of Soviet origin. It is a refurbished and modernized variant of the World War 2 era B-4 howitzer. No B-4M were ever produced new from the factory.
The B-4M is based on a refurbished World War 2 era B-4 towed howitzer. The B-4M is an improved design that replaces the most iconic feature of the B-4, the tracked chassis. The wheeled chassis features four very large and wide pneumatic tires. These are fitted to bogies that allow the wheels to be raised in the firing position.
The B-4M fires the same heavy powerful 203mm shells as the B-4, since the ordnance isn't changed. The maximum range is a modest 18 km due to its relatively short barrel. The rate of fire is rather limited at one round every 1 or 2 minutes. In the 1970's a nuclear shell was developed for the B-4M and 2S7 Pion. This is the 3BV2 Kleshchevina and had a 0.5 kT yield.
The B-4M was towed by the AT-T artillery tractor. This powerful artillery tractor was derived from the T-55 tank. The maximum tow speed for the B-4M was 30 km/h. In modern mechanized warfare a speed of 30 km/h isn't fast at all, but this was still over twice as fast as the maximum tow speed of the regular B-4.
The B-4M was used by Soviet forces. At least 105 were converted from existing B-4 that had been refurbished several years earlier. The B-4M was gradually replaced over several decades by a range of weapons. These include a small number of 180mm S-23 howitzers, various tactical missiles, the 2S4 Tyulpan self-propelled heavy mortar and finally the 2S7 Pion self-propelled howitzer.
The B-4M was not produced new, but is a refurbishment of the World War 2 era B-4 towed howitzer.
The B-4M cannot fire the ammunition developed for the 2S7 Pion, even though their ordnance is of similar caliber. The single exception is the 3BV2 nuclear shell.
The B-4M was often towed by the AT-T artillery tractor, which is based on the chassis of the T-55 main battle tank.
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