I was surprised that they would produce this model with an extra set of barrels. Everything is serial numbered the same. Suppose it is quite possible that the Full choked set of barrels had the chambers lengthened and the gunsmith stamped 3 IN on both barrel flats. Thank you for the info on the 3" 12 back then. This SxS has heavy breech's, would like to try some 2 3/4 bismuth in it, but am worried about pressures. Stock in great shape now, better use one of my newer 12 SxSs as I have been doing. Again thanks.