The Geissele Super Duty MOD1 5.56mm 14.5" Heavy Barrel (.750 Journal) DDC Complete Upper Receiver is a premium upper receiver assembly designed to mate with any AR-15 lower. Built around a 14.5" cold hammer forged and chrome-lined barrel with a 1:7 twist and a heavy (.750 gas journal) profile, this upper delivers enhanced rigidity and heat capacity while maintaining smooth cycling via a mid-length gas system and Super Compact gas block. The upper features Geissele’s MK16 M-LOK free-float rail (center tabbed for torque resistance), a HUXWRX Flash Hider-QD muzzle device, a Nanoweapon Reliability Enhanced BCG with Stressproof bolt, and an Airborne charging handle. Finished in Distressed Diamond Cut (DDC), the 08-626S is optics-ready and built in the USA for rugged, long-term performance — ideal for builds where durability, heat management, and precision matter.