WHAT DOES COLT 20 INCH CLASSIC UPPER MEAN?

Bore Situation: The bore is shiny, the rifling is sharp. There isn't a erosion inside the bore. The feed ramps are clean and glossy. During this author’s belief the bore rates 9/ten.*Beauty blemishes tend not to have an impact on in shape or performance in the upper team. All BCM upper groups are head spaced and examination fired for performance