Guys, its the HEAD DIAMETER that really counts.
GONRA knows authentic 7.63 mm Mauser cases can stick in 7.62 mm Tokarev chambers.
Gotta hava pyle of both specimens (1930's, WWII era) from yer catridge collection to measure.
You can also prove almost anything you want if you grab individual sloppy manufacture factory WW II specimens
and some post war commercial specimens designed to "chamber in anything".