280mm m.1939 Br-5 Heavy Mortar
The 280mm m.1939 Br-5 was a Russian heavy mortar produced in Stalingrad between 1939 and 1940. It was the heaviest artillery piece used by the Russians during WWII.
The Br-5 suffered from poor mobility because the barrel was transported separately. The Br-5 tracked carriage was typically towed by the Voroshilovets tractor with the gun towed on a Br-10 wheeled cart by a Komintern tractor.
The Br-5 was used in Finland during the Winter War as well as the Battle for Berlin.