Guntec USA AR .308 Upper Receiver Assembly Kit. 308 Charging Handle .308 Trap Door Assembly Specifications for Guntec USA AR.308 Cal Upper Receiver Assembly Kit: Manufacturer: Guntec USA Color: Black Finish: Anodized Caliber: .308 Winchester Weight: 10 oz Included Accessories: .308 Trap Door Assembly Forward Assist Assembly .308 Charging Handle Condition: New Projectile Caliber: .308 Caliber Package Contents: Guntec USA AR.308 Cal Upper Receiver Assembly Kit GUNTEC USA GT-URK-308: AR.308 Caliber Upper Receiver Assembly Kit