AR Performance(ARP) 5.56 Scout in Stainless Steel is a light weight profile with a slightly different taper to stiffen the barrel. Chambered in 223 Wylde, shoots 223 and 556 ammo and is more accurate. Twist is 1:7.7, Mid-length gas system and the muzzle is threaded 1/2x28. Finish is shiny, not matte.