The first T-28 prototype were completed in 1932, this having a 45mm gun as main armament. In October of 1932, production of the T-28 were accepted after that improvements had been made. The Red Putilov Factory in Leningrad were assigned to manufacture the T-28 medium tanks. In February of 1933, the first 10 series produced T-28 tanks were handed over to the RKKA, and these took prt in the May Parade in Moscow. On August 11th of 1933 the T-28 were officially accepted by the RKKA. The standard T-28 production model (T-28 Model 1934) used the same main and sub-turrets as the T-35 heavy tank. This version remianed in production from 1934 to 1938, when an improved 76.2mm L-10 gun replaced the old 76.2mm Model 1927/32 gun. The T-28 Model 1938 remained in production until 1940, and during the early fighting in Finland in 1940, at least two brigades used T-28 tanks, the 10th and 20th Heavy Tank Brigades. These units suffered heavily, as Finnish anti-tank gunners found them to be clumsy and thinly armored. A crash programme was initiated to up-armor the T-28, and many T-28 Model 1938 were provided with applique armor and was respecified as T-28E. The final version, the T-28 Model 1940, had the same conical turret as late T-35 Model 1938s and 12 vehicles were built. Several variants were based on the T-28 but none was accepted for production. In 1940, a bridgelayer-prototype, IT-28, was built at Kirow. 7 x T-28 tanks were captured by the Finnish army between 1939 and 1944. Two T-28 were exported to Turkey in 1935, and eventually one to Spain. About 600 T-28 tanks were manufactured from 1934 to 1940. They equipped four heavy tank brigades, three of which used them exclusively. The fourth one was the 5th Heavy Tank Regiment, with two battalions of T-35s and a third battalion of T-28s.
P-40 AAMG mount on T-28 main turret.
Specifications (T-28 Model 1938):