Just picked up a very nice Winchester Mdl 21 Trap vent rib. Has the tight full barrel on the right and the mod on the left. Now I know Winchester would do almost whatever a customer specified, but what would be the reasoning for going from the traditional more open right barrel to the tight barrel on the right hand side. Figured I would get plenty of opinions, and is there anything written by Winchester for doing so? I have seen several Mdl 21 Traps configured this same way. JW