Geissele Automatics Geissele Super HBAR MOD1 5.56mm 16″ Bbl (.812 Journal, 5/8×24) DDC Complete Upper Receiver 08-617S

The Geissele Super HBAR MOD1 5.56mm 16″ Bbl 08-617S ships as a genuinely complete upper, not a barrel and rail waiting on the rest of the build. The Nanoweapon-coated Reliability Enhanced BCG, Airborne Charging Handle, and HUXWRX Flash Hider-QD muzzle device all come installed, so a compatible lower is close to the only thing left to add. This Geissele Super HBAR Upper is built around a Super Heavy barrel profile, a step beyond the standard Heavy profile used elsewhere in the Super Duty MOD1 line, engineered specifically for high-volume, sustained fire where heat management matters more than anywhere else on the rifle. The 16″ barrel is cold hammer forged and chrome lined with a 1-7 twist, paired with a .812 gas journal, a custom-reinforced Super HBAR gas block, and a straight, extra-thick Super HBAR gas tube, all working together to pull heat away from the system faster than a standard gas setup can manage. Geissele’s own proprietary gas length, tuned specifically for this configuration, keeps cycling smooth even as round counts climb. A 15″ MK16 Super Modular Rail mates to the upper through Geissele’s center aligning tab, removing any chance of rail rotation, with stainless steel QD inserts reinforcing sling attachment points. This Geissele 16 upper threads 5/8×24 for muzzle devices, matching the HUXWRX Flash Hider-QD already mounted at the muzzle. Finished in Geissele’s Desert Dirt Color and weighing approximately 5.5 lbs, this Geissele Super Duty 16″ upper is built for anyone running high volumes of fire who needs the barrel and gas system to keep up without losing accuracy to heat. Key Features Ships complete with BCG, charging handle, and muzzle device installed Super Heavy barrel profile, cold hammer forged and chrome lined .812 gas journal with reinforced Super HBAR gas block and gas tube Geissele-length gas system tuned for sustained fire 15″ MK16 Super Modular Rail via center aligning tab Nanoweapon-coated Reliability Enhanced BCG with Stressproof Bolt HUXWRX Flash Hider-QD muzzle device, 5/8×24 thread Weighs approximately 5.5 lbs, finished in Desert Dirt Color Geissele Automatics Geissele Super HBAR MOD1 5.56mm 16″ Bbl (.812 Journal, 5/8×24) DDC Complete Upper Receiver 08-617S