The ACR, a two-position (suppressed and non-suppressed), short-stroke, gas-piston system of operation; modular, interchangeable bolt heads, barrels, magazines, buttstocks and handguards; an aluminum upper receiver and a polymer lower receiver; a cold hammer-forged, free-floating barrel; and ambidexterous controls. In short, it's innovative and badass.
gaylord
"Don't ask, don't tell"