Not only does a vented rib on a SXS not transmit barrel heat to the top surface of the rib thereby creating distorting heat waves but it also allows for a rib positioned higher at the breech end than at the muzzles (in order to have a more elevated POI) while eliminating the additional weight necessitated by a solid rib thick enough to replicate the same POI characteristics as the vented rib.
Not True
Rib configuration has nothing to do w/ the POI of a shotgun. That is determined by the relative positions of the shooting eye and the centerline of the bore since it is generally considered that even if one does not look at it, the end of the bbl or front bead is guide relative to the target. All the rib does is provide a "sight picture".
I have a Mirage that I have gathered two additional bbls for. It has 70cm, 72cm, and 76cm bbls. The 70 has a flat rib, the 72 a 2mm step and the 76 a 4mm step. Vastly different "sight pictures", but they all shoot to the same POI because the front beads are all the same height relative to bore center and that is my target sighting ref for the pattern board.
Draw your own picture if you need. You will see that you can wave the rib around all you want under the line between the eye and the front sight and it affects nothing.
have a day
Dr.WtS
