Daniel Defense MK12, Semi-automatic Rifle, 223 Rem/556NATO, 18 Barrel, Matte Finish, Black, Daniel Defense Furniture, 32 Round, 1 Magazine 02-142-13175-047 The MK12 is constructed around an 18-inch Stainless Steel barrel with a chamber created during the Cold Hammer Forging process, which ensures the most precise alignment of the chamber to the bore possible. This, along with being DLC finished, equates to unprecedented accuracy and durability. The MK12 barrel is engineered with a rifle-length direct impingement gas system and utilizes the MK12 gas block, which is built to Crane Specifications for USSOCOM.