Carbines are for the weak men and strong girls. And the 300m+ battle space is way over emphasized by the Mattel fans. The zombies aren't real.
Even ol' coots on the interwebs can do minute 'o baddy at 230 yards using a bead sight and off the shelf slugs.
Besides, who wants to watch the bad guy just drop when you can use him as a human spray paint can? Why would you want something that is liable to break or adjustably collapse if you only want to smash some perp face with the stock?