I,m taking a shot in the dark here but I think they're 3 different contours on the standard 22" barrel not counting the superlite. Even those will vary by the bore size with the largest bore having the lowest weight on any given contour. The contour being how much the barrel tappers down from the fore arm to the muzzle. Sight heights vary on these also. The higher the sight the smaller the muzzle. We really need to have a weight and measures sticky so we will know what our finished gun will weigh when ordering different barrels.