Geissele Automatics Geissele Super Duty MOD1 5.56mm 16″ Heavy Bbl (.750 Journal) DDC Complete Upper Receiver 08-627S

The Geissele Super Duty MOD1 5.56mm 16″ Heavy Bbl 08-627S ships as a genuinely complete upper, not a barrel and rail waiting on the rest of the build. Bolt carrier group, charging handle, and muzzle device all come installed, so mating it to a compatible lower is close to the last step in getting it running. At the center of this Geissele Super Duty MOD1 16 upper is a 16″ heavy profile barrel, cold hammer forged and chrome lined with a 1-7 twist, built for extended shooting sessions where a standard-profile barrel would start losing accuracy to heat. Geissele’s proprietary gas length, tuned specifically for this configuration rather than a stock mid-length or rifle-length system, pairs with a Super Compact gas block at a .750 gas journal for smooth, consistent cycling. The upper connects to a 15″ MK16 Super Modular Rail through Geissele’s center aligning tab, eliminating any chance of rail rotation once torqued down. Cycling the bolt is the Nanoweapon-coated Reliability Enhanced BCG, built around the Stressproof Bolt and high pressure tested for a service life well past a standard mil-spec bolt. A HUXWRX Flash Hider-QD muzzle device comes mounted at the end of the barrel, and an Airborne Charging Handle rounds out the assembly, ambidextrous and low-profile enough to avoid catching on gear. Finished in Geissele’s Geissele Super Duty DDC and weighing approximately 5.1 lbs, this Geissele Super Duty upper receiver is built to run as-is once paired with a lower. Key Features Ships complete with BCG, charging handle, and muzzle device installed 16″ heavy profile barrel, cold hammer forged and chrome lined Geissele-length gas system tuned specifically for this configuration 15″ MK16 Super Modular Rail via center aligning tab Nanoweapon-coated Reliability Enhanced BCG with Stressproof Bolt HUXWRX Flash Hider-QD muzzle device Airborne Charging Handle for ambidextrous, low-snag operation Weighs approximately 5.1 lbs, finished in Desert Dirt Color Geissele Automatics Geissele Super Duty MOD1 5.56mm 16″ Heavy Bbl (.750 Journal) DDC Complete Upper Receiver 08-627S