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 mounting 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 stopping development of the prototype to use T-100 as a self-propelled gun/tank destroyer armed with the 100 and 130 mm naval guns.

[2] There were several complaints: the mantlet was installed with no regard for balance, which made aiming difficult, the fighting compartment was too cramped, and there were several issues with the running gear.

[2] In a report from April 1st, 1941, a commission noted that the fighting compartment, gun, engine, and transmission parts of the prototype were covered in rust due to poor storage.

[3] With the start of Operation Barbarossa, as the German forces approached Moscow, the two SU-14 and T-100Y prototypes were shipped to Kazan in the fall of 1941, where they served as specimens in technical courses, returning to Kubinka in 1943.

[2] A spacious, fully enclosed casemate with a height of 3.29 meters was welded from armor plates 60 mm thick all-around.

A feature of the gun was a 55-caliber barrel, which provided the projectile with an initial velocity of over 800 m/s, so even with an elevation angle of about 30 °, it was possible to reach a firing range of about 20 km.