The Jacob Grey Ultralight Complete Upper Assembly was designed with the next generation AR-15 in mind. This AR-15 complete upper assembly is built around the 7075-T6 billet upper receiver specifically machined and cut in areas where excess material was unnecessary and areas that see excess use and wear, reinforced and strengthened to give a sleek, refined look, without losing the classic lines of the AR-15 platform. It comes standard with the JG designed free float 7-sided M-LOK hand-guard that is also lightweight and leaves plenty of room for customization or the addition of numerous accessories available for the AR-15 platform. The barrel is chambered in 300 Blackout with a 1:8 twist rate. The barrel is machined from 4150 chrome moly steel and black Nitride finished for corrosion resistance and accuracy. Each barrel is individually head-spaced to the Carpenter 158 bolt. Combined with the 8620 steel carrier and black Nitride finish, this complete upper assembly is extremely reliable and smooth shooting. DISCLAIMER: Firearm specifications are subject to change at any time based on availability and supply chain shortage. Specifications for Jacob Grey Firearms Ultralight 300 BO Complete Upper Assembly: Manufacturer: Jacob Grey Firearms Cartridge: .300 AAC Blackout Barrel Profile: Pistol Caliber Taper, Medium Taper Gas System Length: Pistol Length Barrel Twist Rate: 1-8 Threads per Inch: 5/8x24 Handguard Type: Free-Float Muzzle Device: Brake Finish: Type III Class 2 Hardcoat Anodized Color: Black Fabric/Material: Aerospace Aluminum Gas Block Journal Size-Diameter: .075 in Handguard Style: Round Rail Attachment/Mount Type: M-LOK Gun Rail: M-LOK Gun Type: Rifle Gun Make: AR Platform Gun Model: AR-15 Weight: 7.7 oz Barrel Material: Chrome Moly Gas Block Journal Size-Length: 1.9 in Bolt Carrier Group Included: MIL-SPEC Charging Handle Included: MIL-SPEC Features of Jacob Grey Firearms Ultralight 300 BO Complete Upper Assembly Compatible with most aftermarket/OEM handguards featuring indexing tabs Billet 7075-T6 aerospace aluminum Jacob Grey lightweight design M4 feed ramps Machined T-marks Laser engraved logo MIL-A-8625F Type III Class 2 hardcoat anodized flat black finish Compatible with MIL-SPEC AR upper receiver parts JG ULTRALIGHT Handguard Package Contents: Jacob Grey Firearms Ultralight 300 BO Complete Upper Assembly