CMMG Mk57 Barrel, 5.7X 28MM, 8" Barrel, 1:9 Twist, Black Finish, Includes BCG, Fits AR Rifles 57D18B1 Out of stock. Check back later... Price: $424.95 Notify me when this item is back in stock (log in required) Description Details Reviews Shipping info CMMG IS A LEADING MANUFACTURER OF AR-15 RIFLES" 22LR AR-15 CONVERSION KITS AND ACCESSORIES. Precise Manufacturing Long Term Reliability Durable Construction UPC: 816422029129Manufacturer: CMMGModel: 57D18B1Caliber: 5.7x28mmCategory: PartsOtherUpper receiverStock: 0Unit/Measure: ea This item may be shipped directly to your home address, unless you live in a restricted state.