Here is a pristine Pro-Rib for a 30” Remington barrel. It adds 3/4” of height for a more ‘heads up’ shooting style. Nothing against the Add-a-Rib, but the quality of the ProRib is far superior IMO. Adds only 2.5 ounces. Easily installed and removed with 3M VHB 5952 tape. $185 shipped. New cost is $300 plus $30 shipping.
Front and mid beads must be removed. Or, if you are skilled, you can leave the mid bead and drill a pilot hole in the rib where the mid bead sits.