Interesting that this SxS has no rear sight, for the micro-groove barrel.
Looks like it would be a comfortable gun to shoot, with shot or patched ball.
Forsyth wrote that the height of the breech, should give the proper elevation for point blank shooting.
With my own 14 bore rifle, the elevation of the folded leaves does exactly this, if point blank range is for 50yards for plinking with the close range target load, or 100 yards with the moose charge.