Diameter - .625", .750", .850" or 1" Bull. Your choice. Twist rate 223 Remington, 223 Wylde or 5.56MM - 1 x 7, 8, 9, 10, 12 & 14 Your choice. Barrel Metal - 416 Stainless Steel or 4140 Chrome Moly Steel *In the white UnFinished is Included or Full Black Oxide of complete...