Chamberings: 5.56 NATO. Features a Nanoweapon-coated Surefire Closed-Tine Warcomp mounted to a 16" mag phosphate cold hammer-forged, chrome-lined Geissele barrel. Twist: 1:7". Gas system: Geissele length, with Geissele Super Compact gas block. Trigger: SSA-E X with Lightning Bow trigger, a nanocoated, two-stage unit. BCG: Machined from mil-spec 8620 steel, properly torqued and staked chrome-lined gas key. Lower: Machined from 7075-T6 aluminum with Geissele’s Ultra Duty Lower Parts Kit. Ambidextrous Super Configurable safety and Ultra Precision triggerguard. Mil-spec Geissele Buffer Tube with Super-42 in H2 buffer ensures this rifle is properly tuned out of the box. 15 MK16 Super Modular Rail mates to Super Duty Upper Receiver via a center aligning tab. Sights: None. Grips: Geissele Rifle Grip. Rails: 15". MK16 Super Modular. Stock: B5 Enhanced Sopmod. No magazine. Colors: Luna Black, DDC (Desert Dirt Color), ODG (OD Green). Add $225 for the 14.5". barrel with a Nanocoated Surefire Closed-Tine Flash Hider, pinned and welded. Introduced 2020. Mod1 Rifle adds HUXWRX Flash Hider-QD 556 suppressor-ready muzzle device, updated MK16 Super Modular Rail with press-fit stainless steel Quick Disconnect (QD) inserts, A17 Grip, and QD Sling Mount Endplate.