So...let me get this straight.
If I take a 270 case, shorten it so it holds less powder,neck it up .007 thou,and make it go slower, it gets "better"?
Did I get that right?
If you have to ask, you are not ready to understand. Keep it up and enlightenment will be yours.
In short, it is just so, that the 7x57 is just so much more "just so".
Trusting to having cleared up this endless enigma, I leave you to your own devices.