Jerry.......we have made over the years many copies of Manton barrels such as you describe. Copied from an original
barrel sent to us by Lynton McKenzie. It is full octagon tapered at the breech, going to 16 flats for about 3", then into
a rather fancy set of rings, then round tapered, going to straight round toward the muzzle....no flair. Pretty barrels, about 32", or could be made into any length................Don