I was looking in other old catalogs but find the 9x63 only in the steigleder. Ernst(ernesto for his south american friends)Steigleder had have his shop in the middle of berlin to being near of his gentleman customer's. he chamber rifle#s for a lot of unusual caliber's. also for the swedish 9,3x57 which is very rare in old german catalogs. I think that he was seeing a lot of foreign visitor's in his shop who came to berlin.
if the german 62-63 mm case have something to do with the US military round? it all starts with the 8x57I and IR and there was a lot of wildcating in this time. the 9,3x74R from 1904 is also a 8x57IR basic round. there are 8x75 and 8x75S cartridges. possible that they look on the 30 06 but not nessesary.