Speaking of cartridge/case design, here's an interesting comparison:
... The .308 was the first large-production military cartridge to fundamentally re-think cartridge proportions...
That sounds to me like Greyfox has hit the nail on the head. Nothing new in the world of cartridge design.
Imagine for just a moment if instead of scaling the .30-'06 cartridge design down for development of the AR-15, Eugene Stoner had instead asked Palmisano and Pindell to design a cartridge for his new military rifle. They would likely have come up with something like the 6 PPC (which they later did for bench rest shooting) -- in other words, a short, stubby case, somewhat similar to the short magnums that featured in the beginning of this discussion. Perhaps that would not have made the shoulder angle so steep, so it would feed more reliably in a military rifle and machine gun. But they would most likely not have kept the .30-'06 proportions.
Perhaps they would have gone a little larger -- say, the 6.5 PPC, or a little smaller -- say the .22 PPC. Of course the .22 PPC is not much different from the .220 Russian, Palmisano and Pindell's parent cartridge for the 6 PPC....
Sounds to me like an interesting subject for a longer discussion!
