The Geissele Super Duty 5.56mm 16" Heavy Bbl 08-660S gives builders a duty-grade foundation without locking them into a specific BCG, charging handle, or muzzle device, that part stays entirely up to you. What does come installed is the barrel, gas system, and rail, already mated and ready to go. Machined and cold hammer forged in-house at Geissele's North Wales, PA facility, the 16" heavy profile barrel is chrome lined with a 1-7 twist, built to handle extended strings of fire without the accuracy loss a standard-profile barrel runs into as it heats up. Geissele's own proprietary gas length, tuned specifically for this configuration rather than a generic mid-length system, pairs with a Super Compact gas block at a .750 gas journal and a .075" gas port for consistent, reliable cycling. This Geissele Super Duty 16" upper connects to a 15" MK16 Super Modular Rail through Geissele's center aligning tab, a mating system that removes any chance of rail rotation once it's torqued down. "Stripped" here refers specifically to the missing BCG, charging handle, and muzzle device, not the rail, which ships already attached to the receiver. Finished in Geissele's Desert Dirt Color and weighing approximately 4.1 lbs, this Geissele stripped upper gives precision, duty, or long-distance builds a solid, USA-made starting point once the remaining components go in. Key Features 16" heavy profile barrel, cold hammer forged and chrome lined 1-7 twist rate for versatile 5.56 NATO performance Geissele-length gas system tuned specifically for this configuration Super Compact gas block with .750 gas journal Includes a 15" MK16 Super Modular Rail via center aligning tab No BCG, charging handle, or muzzle device included Weighs approximately 4.1 lbs Finished in Geissele's Desert Dirt Color Geissele Super Duty 5.56mm 16" Heavy Bbl (.750 Journal) DDC Stripped Upper Receiver (No Charging Handle, Muzzle Device, or BCG) 08-660S