Geissele 08-543S Super Duty MOD1 5.56 NATO 10.3" 1:7" CHF Chrome Lined Bbl DDC Complete Upper Receiver GroupThe Geissele Super Duty MOD1 5.56 NATO 10.3" 1:7" CHF Chrome Lined Bbl DDC Complete Upper Receiver Group 08-543S is a high-quality upper receiver assembly for AR-15 style rifles. It features a 10.3-inch Cold Hammer Forged (CHF) chrome-lined barrel with a 1:7" twist rate, which is optimal for stabilizing a wide range of bullet weights commonly used in 5.56mm NATO ammunition. The Geissele 08-543S upper receiver group is finished in DDC (Desert Dirt Color), providing durability and resistance to corrosion. Geissele is known for producing precision-engineered firearm components, and this upper receiver group is designed to meet the demanding standards of military and law enforcement users as well as civilian enthusiasts..yellow-box p {font-size:16px}.special-tab {color: #FFFFFF}.yellow-box ul li {font-size: 16px;}The Geissele Super Duty MOD1 Complete Upper Receiver offers top-tier components for a custom AR build. Geissele Super Duty MOD1 Upper Receiver is precision-machined, cold hammer forged barrel is made from high-quality steel, coated with manganese phosphate and chrome lining for durability against the elements. The HUXWRX Flash Hider-QD 556 muzzle device enhances performance and is suppressor-ready. The included Reliability Enhanced Bolt Carrier Group features Nanoweapon coating, properly staked gas key, and a cam pin machined from H13 tool steel for corrosion and wear resistance. Extended upper rails improve stability and feeding reliability, while the Stressproof Bolt offers superior strength and fatigue resistance. The updated MK16 Super Modular Rail ensures a secure fit for a variety of optics, including iron sights, red dots, scopes, and thermal/night vision devices. Features of the Geissele Super Duty MOD1 Upper ReceiverPrecision machined, cold hammer forged barrelHUXWRX Flash Hider-QD 556 muzzle deviceGeissele own Reliability Enhanced Bolt Carrier GroupGeissele Stressproof BoltAirborne Charging HandleUpdated MK16 Super Modular Geissele Super Duty MOD1 5.56 NATO 10.3" 1:7" CHF Chrome Lined Bbl DDC Complete Upper Receiver Group 08-543S