I was looking for something that was accurate, fast and had knock down power. The AK-47 while a cool Hollywood gun is too slow, cumbersome and not that accurate. The 5.56 nato round is just plain silly. There is a reason why our soldiers can't stand it. We call it lack of knock down power.
I have plenty of AR-15 in .223, but the 223 lacks power & range, I'll stick with the 308 win.
How much range do you need? I think that if you shot it out of a light weight. magazine fed, air cooled, gas operated, shoulder fired weapon that you might be able to get a max effective range of 800m for an area target and 550m for a point target... I've shot 500 yards accurately... How is one semi-automatic faster than another? Try this... It seems to meet all of your criteria... Barrett