Defining "Assault Rifle"

Let's use the US military's definition.

Assault rifles are short, compact, selective-fire weapons that fire a cartridge intermediate in power between submachinegun and rifle cartridges … Assault rifles have mild recoil characteristics and, because of this, are capable of delivering effective full-automatic fire at ranges up to 300 meters.

Now, for those of you who are challenged by such complex words and sentences, a breakdown.

...assault rifles have at least three characteristics: (1) capable of selective fire (which includes fully automatic fire), (2) fire an intermediate cartridge,  and (3) mild recoil.

So.  If we were to purchase an AR in .308 (e.g.), even that "mild recoil" condition would go away.  

The .223 cartridge is not too popular with US troops in Afghanistan because it is simply not powerful enough to take down enemies at 300++ yards--something that the AK-pattern rifle can do with its .308-equivalent chambering.   For that matter, the AK is not exactly "short."

Note carefully that the military description does not include any reference to the number of rounds in a magazine.

HT:  Captain