.280 Enfield...Ahead of its time

[Tony Williams]

TO be honest it is all academic, the way to do this properly is to decide the effect you want to deliver, and then design the bullet to do that, and a cartridge to propel it. Things like the Grendel and the SPC are still tied to the available parent cases - a company with resonable resources could start with a greenfield design. I think this is what is suggested in the Optimised Calibre discussion (I've been away and have not had the chance to read it yet).

Yes, of course that is the way to do it. But it isn't the choice of parent cases which is the constraint on cartridge design, it's the maximum permissible overall length for the round to fit within an AR-15 action. That limitation is what is causing both the 6.5mm Grendel and 6.8mm SPC to be less than optimal.