Jack,
The quarter rib that I have used in the past is the blank made by Dakota for the Shilen and Douglas tapers 3,4,&5. Search "quarter rib" in either Brownells or Midway as a few sources. Midway offers all 6 tapers metnioned where as Brownells only offers a subset, both are around 70 bucks or so, but sometimes on sale for 60 or so.
The Shilen profile of the shank is longer than the Douglas, I have only used the ribs with Shilen so far, just what I had. If one extends the rib to the rear over the receiver, the extra length comes at shank expense, so just something to keep in mind when doing planning.
The Dakota ribs that I have used; Shilen taper 3 and 4, fit the contour of the as shipped Shilen taper very nicely, but really fit super in one spot one might say. These are blanks, that is the bottom curveatures to the barrel are there but the top has to be machined for the rings or rear sights of the day. The Dakota ribs that I have used, were 1/2 wide; so work well for Talley and Ruger type rings, but the wider Weaver mounts would have some additional work for a submount.
If you have the No.1 book by Clayton, page 86 has such a rib machined for over the receiver with Talley vertical rings. Of course, lots of pictures in the custom no.1 area in this book that show ribs......of all types.
The Dakota rib is nice machineable steel, that blues well. I inquired about other rib tapers at Dakota a few years ago, and they stated then that is the crop, as I wanted one for lighter tapers.
The quarter ribs done pure custom from a billet are fairly labor intensive, hence the difference in price. Pure custom is just that, anything you want, but $ and time; and to find a gunsmith that will spend that time these days......fitting of the rib to the barrel and machining for ring attachment points, not to say perhaps irons as well, can be lots of spent time comparatively speaking.
The Dakota is a nice product at least to me, but is not a direct bolt on.
One can use a Ruger factory No.1B rib as is on a Shilen 4 without much hassle, but in the traditonal factory postioning(only on barrel proper). On this particular application, if one takes off a bit of the Shilen #4 shank, the No.1B forend fits pretty good.
Roof