the average barrel length is 14" most split into 2 parts the front being ported and approx. .700 bore the back being the control bore which can range from .675-.695 the average size this year seems to be .689.
according to trials its only the 1st 6-7 inches that is needed for optimal accuracy.
you don't find many short barrels anymore but I have seen some short tips for the freak and dye backs