I think what nks was saying is that belted cases are not dependant on the cases dimension from the base to the shoulder to ensure the round is held tight against the firing pin.
I really feel there are way to many new magnums being released recently. I wish that Ruger had released a 7mm,308, 338, 375 series of rounds before the recent barage of new rounds. Its a round thatreally makes sense and would be a great option for building a high performance rifle off the standard magnum bolt face that is so common. In 308 it would exceed the ballistics of the 300WBY.