The Geissele Super Duty 5.56mm 16" stripped upper 08-660B is built around a 16" heavy profile barrel, cold hammer forged and chrome lined with a 1-7 twist, machined and finished entirely at Geissele's own North Wales, PA facility rather than sourced from an outside barrel maker. Unlike a bare receiver, this Geissele stripped upper ships with its rail already mated in place. The upper connects to a 15" MK16 Super Modular Rail through Geissele's center aligning tab, a design that eliminates any chance of rail rotation once torqued down, a detail operators running this rail family have come to rely on. "Stripped" here means no bolt carrier group, charging handle, or muzzle device, not a bare receiver waiting on a handguard. Geissele's own proprietary gas length, tuned specifically for this barrel and rail combination rather than a generic mid-length system, pairs with a Super Compact gas block at a .750 gas journal for smooth, consistent cycling. That precisely balanced gas system, especially when paired with Geissele's Super 42 braided buffer spring, sold separately, helps minimize felt recoil while keeping cycling reliable even in adverse conditions. At approximately 4.1 lbs, this Geissele Upper receiver stripped carries real heft where it counts without becoming unwieldy once the rest of the build comes together. Finished in black and built entirely in the USA, this Geissele 16 upper gives builders a rugged, optics-ready foundation for precision, duty, or range-oriented rifle configurations once paired with a compatible lower, BCG, charging handle, and muzzle device. Key Features 16" heavy profile barrel, cold hammer forged and chrome lined 1-7 twist rate for stability across 5.56x45mm NATO loads Includes a 15" MK16 Super Modular Rail via center aligning tab Geissele-length gas system tuned specifically for this configuration Super Compact gas block with .750 gas journal Weighs approximately 4.1 lbs No BCG, charging handle, or muzzle device included Machined and finished in the USA Geissele Super Duty 5.56mm 16" Heavy Bbl (.750 Journal) Black Stripped Upper Receiver (No Charging Handle, Muzzle Device, or BCG) 08-660B