I don’t know why he keeps calling it a “battle rifle,” as a battle rifle is a semi-automatic or select-fire service rifle chambered in a full-power rifle cartridge. I think he’s trying to avoid the term “assault rifle” even though it’s not that, either. An assault rifle must be capable of select fire; that’s just a rifle.
The Daewoo K2 is a gas operated, selective fire, magazine fed weapon. The K1rifle and K1A1carbine differs from the K2 rifle by different gas system, shorter barrel with different muzzle compensator / flash hider (K1A1 carbine only), and different type of buttstock.
The K2 gas system features a long stroke gas piston, located above the barrel. The bolt group is more or less similar in design to the M16 design, with rotating bolt that have 7 lugs and locks directly into the barrel extension. The cocking handle is attached to the right side of the bolt carrier and reciprocates when gun is fired. Some sources, however, stated that the K1 rifle had the gas system similar to the one found in AR-15/M16 rifles, with no separate gas piston and gases being directed straight into the bolt carrier. The return spring with its guide rod is located behind and partially inside the gas piston rod, and, unlike the M16, does not take space in the buttstock, allowing for folding or completely retractable butt to be used.
The receiver is generally similar in design to the M16 rifle, and is made from two halves, upper and lower, machined from the aluminum alloy forgings, and linked by two cross-pins. It must be noted, however, that Daewoo receivers are NOT interchangeable with any AR-15/M16 type receivers.