Weighing 68 tonnes, thickly armoured and armed with a 130mm S-70 long-barrelled gun, it was the largest and heaviest member of the IS family. The armour was engineered in a similar fashion to the IS-3, with a pike nose on the upper glacis. When shot at frontally, the extreme angle that the pike nose presents results in a much higher likelihood of a ricochet. Thus, the armour protection could be enhanced without having to use excessive amounts of materials.
However, if the pike nose was shot in at a sideways angle, it would not have a relative thickness high enough to ricochet the shell. In spite of its weight, it was easy to drive due to numerous hydraulic assists. The loaders noted that the IS-7 was comfortable and that the autoloader was easy to use. It was also able to achieve a top speed of 60 km/h thanks to a 1050-horsepower engine giving it a power to weight ratio of 15.4 hp/tonne, a ratio superior to most contemporary medium tanks. Its armour was not only immune to the Jagdtiger's 12.8 cm Pak 44 but was even proof to its own 130mm. Due to the reasons unknown, most likely because of the considerable issues arising from its mass (bridges, rail transport - no Soviet/Russian tank accepted into service afterwards exceeded 55 t), the tank never reached the production lines. [Source: wikipedia]