It's most likely 7.62x25 Tokarev, which is loaded substantially hotter than 7.63x25 Mauser. Why it has been loaded into stripper clips when both the TT33 and the PPSh-41 loaded from detachable box magazines is anyones guess, maybe they were still using C96s in some areas and in wartimes obviously weren't very concerned about damaging the old C96s they still had in their armories.
Look on the bright side though, now you have an excuse to own a Tokarev Pistol and there are a bunch of them available from various websites for about $220 on average.