Shop › CMMG ZEROED AR15 ADJSTBLE GAS BLOCK CMMG ZEROED AR15 ADJSTBLE GAS BLOCK $79.95 CMMG ZEROED Adjustable Gas Block, Fits AR-15 with .750" Barrels, Nitride Finish, Black 55DA31F Quantity: Add To Cart Added! CMMG ZEROED Adjustable Gas Block, Fits AR-15 with .750" Barrels, Nitride Finish, Black 55DA31F