Caliber: 5.56 NATO. Barrels: 14.5”, 16”, 18”. Length: 32.5” to 36”. Weight: 6.6 lbs. Geissele cold hammer-forged (CHF) chrome-lined barrel; Super Compact gas block; Mag-Phos-coated Geissele Bolt Carrier Group. Skeletonized MK20 rail, Super 42 braided buffer spring, ambidextrous Geissele Government Charging Handle with low-profile levers. ALG Defense Advanced Combat Trigger. Values are for the 14.5” and 16” barrel models; add 9% for the 18”-barrel variant.