Comparing: IS-3A vs. Caernarvon

In 1956–1957, the Military Armored Forces Academy developed a speculative design for a new loading system on the IS-3 and T-10 heavy tanks. The IS-3 variant featured a double-row ammo rack with an automatic loading system. The crew was reduced to three members: commander, gunner, and driver. The turret was redesigned in order to accommodate the loading mechanism. The vehicle existed only in blueprints.

Development of this infantry support tank started in 1944. The first prototype was ready for trials in 1952. A total of 21 tanks were manufactured but never entered service. Some of the vehicles were later converted into the Conqueror heavy tanks.