Faxon Firearms Duty Series AR-15 5.56 Nato 16in Upper Receiver Gunner Mid Length 1-8 Twist 1/2x28 w/BCG Supressor Black. 56 Complete Upper is a duty-grade ready-to-run upper receiver group designed for reliability balance and consistent performance. Built around Faxons proven 16in Duty Series Gunner Barrel and paired with a smooth mid-length gas system this upper is an excellent choice for training defensive use and general-purpose AR-15 builds. This is a complete upper meaning it ships with a Faxon Superfinished M16 Bolt Carrier Group (Nitride) and a MIL-SPEC charging handleso you can mate it to a compatible AR-15 lower and get running quickly. This model uses a standard A2 flash hider and a Faxon low-profile fixed gas block (non-adjustable). Specifications for Faxon Firearms Duty Series AR-15 5.56 Nato 16in Upper Receiver: Manufacturer: Faxon Firearms Caliber: 5.56x45mm NATO Overall Length: 25.25 in Barrel Length: 16 in Barrel Twist Rate: 1-8 Threads per Inch: 1/2x28 Color: Black Gun Model: AR-15 Fabric/Material: Stainless Steel Gun Make: AR Platform Flutes: No Package Contents: Faxon Firearms Duty Series AR-15 5.56 Nato 16in Upper Receiver What firearm models does the manufacturer say Faxon Firearms Duty Series AR-15 5.56 Nato 16in Upper Receiver is compatible with? The manufacturer says that Faxon Firearms Duty Series AR-15 5.56 Nato 16in Upper Receiver is compatible with AR-15Faxon Firearms FX-URG-D55616GA15-C-SR: Duty Series AR-15 5.56 Nato 16in Upper Receiver Gunner Mid Length 1-8 Twist 1/2x28 w/BCG Supressor Black