50 Roubles Heavy Tank IS-5 (OBJECT 730)

The Object 730 — later designated IS-5 — was a Soviet heavy tank development program that ran from roughly 1949 to 1953, competing internally with the IS-7 and T-10 programs during Stalin's final push to field a next-generation heavy tank. It never entered serial production. The T-10 won that competition, and Object 730 remained a prototype curiosity known primarily to engineers and archivists rather than the soldiers who would have crewed it.

That a commemorative rouble series would reach this far into the prototype register — honoring a vehicle that never left the factory floor in numbers — reflects how thoroughly Russian numismatic programs of the post-Soviet period mined Soviet military development history for subject matter.