the AR15/M16 weapons system isn't a battle worthy weapon in any situation. It performs poorly in arctic, desert, jungle, and any place outside of a gun range. The AR15 wasn't even built for the military, it was built as a target gun, which the Airforce bought and converted to the fully automatic M16. Just before Vietnam, the Army and Marine adopted the M16a1 as it's standard issue weapon...and everybody hated it. It should be replaced ASAP, direct gas operation doesn't work in combat. On a further note, HK's new AR15 uses a short stroke, gas-op piston, similar to the G36, and Kalashnikovs. It affects the accuracy slightly, but makes up for this with superior reliability.