This YHM barrel features a 6.8mm SPC II chamber. Constructed of 4140 chrome moly steel with a threaded muzzle. Phosphate coated to MIL-SPEC with a chrome lined bore for that original military appearance. This barrel is an excellent choice for a general purpose AR rifle build. It is perfectly suited for use at the range in a 3-Gun match or in the field pursuing game. - Surface: Diamond Fluted - Length: 16 - Weight: 1.73 lbs. - Material: 4140 Chrome Moly Steel - Chamber: 6.8mm SPC II - Twist Rate: 1 in 10 - Chrome Lined: Yes - Finish: Manganese Phosphate (Parkerized) - M4 Feed Ramps: Yes - Muzzle Thread Pattern: 1/2-36 - Gas Port Location: Carbine - Exterior Diameter at Gas Port: 0.750