SU - 100Y Self - Propelled Gun The SU - 100Y was a Soviet prototype self - propelled gun , developed from the prototype T - 100 tank . It was developed during the Winter War with Finland to include a 152 mm gun to destroy concrete defensive structures like bunkers and anti - tank obstacles . It did not see service before the end of the war but was brought into use in the Second World War in defence of Moscow . History . In December 1939 , the Northwest Command of the Red Army requested that the N°185 factory develop a vehicle based on the T - 100 . The vehicle had not only to operate as a self - propelled gun , but also to be used to lay bridges , transport explosives , and recover tanks destroyed or damaged on the battlefield . During the development of this vehicle , the ABTU proposed to mount the large , high velocity 152 mm cannon on the T - 100 in order to give it the capacity to destroy bunkers and other strong fixed fortifications . The plant manager at N°185 proposed to stop the development of the prototype to use T - 100 as a self - propelled gun armed with the 100 and 130 mm naval guns . This idea was accepted and on January 8 , 1940 , the plans of the T - 100 - X were finalized and sent to the Izhorskyi factory . The T - 100 - X had a box - shaped fighting compartment and was equipped with the 130 mm B - 13 naval gun . For mobility , kept the torsion bar suspension system , as was the trend in modern tanks of the day . During the development of the prototype the shape of the fighting compartment was modified to reduce ammunition loading times . The new design was the SU - 100Y ( sometimes called T - 100 there ) . The designs of the SU - 100Y were sent to the Izhorskyi factory on February 24 , 1940 and assembly began on the first of the month . The self - propelled gun was tested for the first time on March 14 . As the Winter War was finished , the SU - 100Y never saw combat . During the Winter War it was proposed to modernize the T - 100 with a more powerful armament , the 152 mm M - 10 gun , able to destroy concrete structures , particularly in dragon ' s teeth , a common anti - tank measure amongst Europe ' s fixed fortifications during World War II . A new turret to accommodate the 152 mm howitzer was implemented around March 1940 . This new model was designated T - 100 - Z . However this project was abandoned because of KV - 1 and the 152mm equipped KV - 2 tanks were superior . In April 1940 , the N°185 factory proposed a self - propelled gun ( prototype 103 ) for coastal defence based on the T - 100 and armed with the B - 13 130 mm naval gun installed in a rotating turret with three 7 . 62 mm machine - guns . This project never went beyond the drawing boards . When work was stopped on the T - 100 project , the SU - 100Y was transported to Kubinka in the summer of 1940 . In November 1941 , at the most critical moment of battle in the suburbs of Moscow , the SU - 100Y , together with the 152 mm gun armed experimental SU - 14 and Su - 14 - 1 , was pressed into service in an Independent Artillery Division for Special Duties . Further information of the combat record of the unit has not been made known . Unlike its base model ( T - 100 ) , the SU - 100Y prototype survived the war and is a part of the collection at the Kubinka Tank Museum .