The factory had one style of rib that had a sheet metal cover. It was a piece that folded around the sides and just under the bottom edge on both sides. You can clearly see that style when looking at the rib from the muzzle.
You remove the large screw at the breech end of the rib,,,then any site beads on the rib.
The rib cover pulls off the bbl assembly from the muzzle end.
Rib damage was a quick fix by simple replacement of the rib cover. Sometimes the underlying rib mount itself needed cleaning up depending on how bad the damage was, but the cover had the matting on it, so a new surface is presented.
The rib covers came in slightly long lengths (32/33" IIRC) for fitting.
I think they also used a style of top rib that used a conventional rib mounted on dovetailed posts. Same disassembly means. Should be able to see that style from the muzzle too if it's on there.
If either is dented, some straightening will be needed before you can simply slide the damaged point along.
