Glenn, the very few UK rifles with ribs I've examined all had what appeared to be variations of typical shotgun solid ribs, that is, somewhat hollow inside and soft-soldered to the round barrel's top and then polished to blend in. These were all on straight-taper barrels, though, without a larger stepped chamber area and of course no Nock's Forms either. The straight or straight-taper ribs didn't have a ramp for the front bead, and the full lengths of the tops were patterned by what I assume were roller stamps of some sort. I've also seen a few, usually rook rifles, with their round barrels filed into what I suppose could loosely be called a rib, by simply filing flats into the 10:30 and 1:30 areas of the full length of the barrel thereby creating the illusion of a raised rib portion down the sight centerline.
OTOH, several Continental ribs I've seen were also soldered on but did have a ramp front and an enlarged area at the rear for the open barrel sight. These were usually on less-expensive and largely nondescriptly unsigned sporters of the 'Guild' sort since the more expensive rifles frequently had integral ribs.
Sorry, not a lot of help here.
Regards, Joe
