The only reason I asked is I tripped over the data by accident. I had a K31 in Germany and looked at the 7.5x55 brass and thought it would be a good upgrade for the .308 Marlin eXpress (similar rim between them, so it should feed) then while chasing dimensions for the 7.5x55, I saw the trick: Winchester took the 7x55 and turned the rim down to .473 to fit in standard boltface, and then necked it to 7mm, possibly to hide the subterfuge.
So in a way other than shoulder angles and taper, the .30-284 case is the same, as the original 7.5x55 Swiss, just with the smaller boltface.
Much the same way the .30 Hembrook Short, which is 52mm long based on the .30 Hembrook Long, will be pretty close internally to the 7.5x55, but won't say "Hembrook" on it so off I go making them just, you know, because I can.