I'd love to see Ruger come out with a PCC in 30 Carbine...or something similar. But an AR in 30 Carbine...that's basically 300BLK. The ballistics are pretty similar, with a slight edge to 300blk. Don't get me wrong, I like the cartridge, and the M1 Carbine, and would love to see more offerings chambered for it. But the AR is today what the M1 Carbine was 50 years ago. Part of the appeal is the low cost, ubiquitous parts and ammo, tactical cashé....
Now here's the bit I don't understand, there were millions of carbines made in the 40's, by multiple manufacturers, well before CNC, and they all ran reasonably well (good enough for government work anyway) and were fairly inexpensive. Today, Inland sells reproductions, for well over $1000, and the reviews are mixed at best. Sure seems to me that with modern manufacturing they could run smaller volumes with higher quality at lower costs. Imagine a poly-stocked stainless M1 Carbine...sounds like a fantastic PDW or varmint gun. And a hoot to shoot!