Jim Whisker, when photographing many of the longrifles he captured on film, often accepted the attribution of the owner when there were only initials [or no initials] on a rifle being photographed...assuming the owner had done the necessary homework to identify the maker. But on many rifles where few, if any, examples with fully signed barrels were known, the original owners were at times mistaken in their attributions. We are fortunate today to have more rifles being discovered, often with a last name, or with provenance that identifies the maker if unsigned. Early owners, and even Whisker, did not always have the advantages we have today...including social media such as this site.
Regarding the gun pictured in Jim Whisker's Virginia book, and seeing all the good information that has already been posted in this thread, I think there is a very good chance the gun in the Virginia book was mistakenly identified by the original owner based on limited knowledge and trying to "fit" a name that was "most likely" to be the maker based on initials on the barrel. It is unfortunate that in some of our early longrifle books, the authors did not state clearly whether a rifle was signed with first initial and last name, attributed based on initials, or simply attributed by the owner based on his/her knowledge of longrifles.
Shelby Gallien