The 203 mm howitzer M1931 (B-4) is a rather old weapon developed in 1931 and adopted for service in 1934. The B-4 has a relatively short tube, only 25 calibers long. It has a hydraulic recoil buffer, It was mounted on a full-track (but not self-propelled) carriage in firing position and for short moves. For longer moves, It was transported on a separate two-wheeled tube transporter. The M1931 (B-4) can fires a 98.8-kg HE round to a maximum range of 18,025 meters.
