I think the Dale Johnson lock would have fit a Bucks County nicely but because of serious eye problems never used one in a BC. . The small Siler is too small for a BC and the large Siler doesn't center on the wrist as well as Chambers' Golden Age or the Dale Johnson
I think many more Bucks County LRs would have been built if Shuler type Bplates and TGs had been available. ......the TG I used was a Verner from Goehring and req'd a few hours of alteration and the Bplate had to have the return facets rounded and the "thumbnail" filed in. The biggest deterrent of building a Shuler, or in this case a Verner, is the elongated finial entry pipe. Lately, a Shuler type TG and Bplate are available from one supplier and are quality items.
Many BCs on the market are incomplete {barn guns are excepted} by not having even a bare minimum of BC features....it seems a curved combline makes a LR a BC. .....Fred