Geissele Super Duty MOD1 .300 BLK 8" 1:7" CHF Chrome Lined Bbl Black Complete Upper Receiver Group 08-553B is purpose-built for suppressed short-barrel performance in close-quarters environments and features Geissele's Phased Array® gas system. Designed around an 8-inch cold hammer forged barrel with a 1:7" twist rate, this upper delivers reliable subsonic and supersonic performance. The barrel is chrome lined for extreme durability and corrosion resistance, making it ideal for high round counts and harsh conditions. The included 7" MK16 Super Modular Rail offers a rigid M-LOK platform for mounting accessories while maintaining minimal weight and superior ergonomics. This upper also features a Geissele Airborne Charging Handle, a low-profile pinned gas block, and a HUXWRX QD 762 Flash Hider for suppressor compatibility. Whether for tactical applications or home defense, this complete upper provides exceptional build quality and performance tailored to the .300 Blackout platform. Caliber: .300 Blackout Barrel Length: 8" Barrel Twist Rate: 1:7" Barrel Construction: Cold Hammer Forged, Chrome Lined Gas Block: Geissele Pinned Low-Profile Muzzle Device: HUXWRX Flash Hider-QD 762 Handguard: 7" MK16 Super Modular Rail, M-LOK Charging Handle: Geissele Airborne Charging Handle Finish: Black Part Number: 08-553B Geissele Automatics Geissele Super Duty MOD1 .300 BLK 8" 1:7" CHF Chrome Lined Bbl Black Complete Upper Receiver Group 08-553B