I can be very wrong but I thought the original parent cases back in the 1890's were extremely similar if not the same. But the 7.9 x 57 (8 x 57) case evolved to its present form sometime in the interwar years. As a result of not only projectile diameter difference but also bullet weight and material conservation. Like war effort. The cartridge definitely went thru an evolution period. Think Olson hit on some of this in his Mauser book. Don't remember it all. Have destroyed considerable brain cells since I last read it!
Good luck in your endeavor!
I think the case shape of the 8x57 stayed the same from the time of adoption to the present time.
What changed was bullets. It went from a 236-grain round nose, to a 154-grain spitzer in 1905, to the famous 196-grain SS load of WW2. (SS in this case stands for schweres spitzgeschoss which translates to heavy pointed bullet.)
