I would dispute that either the Superposed or B325 Browning are of chopper lump construction. By definition, a chopper lump barrel has half of the lump forged as part of each barrel. This obviously cannot be the case on an O/U, and the lug is a part of the lower barrel only, with the upper barrel attached to the lower by some means, probably brazing. Just because someone calls an apple an orange doesn't make it so.