That's a recurring idea of mine. WI at the end of June 1941 Beria stages a successful coup against Stalin (maybe disguising it as a sudden "natural" death of the Vozhd) and begins not only to free a sizable part of the detainees in the Gulag, but most of all publicly asks for Western direct help against the Nazis? Could a Western expedition corps (British, for the moment being) be actually sent to the Eastern meatgrinder? And if yes, with what size, and what likely combat results?