.... new cartridges like the 6.5 Creedmoor not utilise the same feature of flatter shoulders?
I am a ballistics novice so please forgive any glaring ignorance, but I thought that one of the major advantages of the AI, for example in 243, was that the brass does not 'grow' with repeated firings from the same case, and that this is mainly on account of the shoulders being a much shallower angle from the horizontal, than the standard 243 round. Makes sense to my rudimentary understanding of the physics involved.
I've been looking at newer calibres and recently my interest's been piqued by the 6.5 Creedmoor, I know it might be a fad etc. etc. but my question is not so much about 'Should I get one' but more... Why did Hornady not design the Ackley feature of the shallower shoulders, in to the cartridge?