H&D Folsom may very well have been the jobber that supplied the wholesaler that supplied the local hardware store or gunshop in Grandpa's home town. I have some Fox doubles that have excruciating detail in the order, but went from the Fox factory to E.K Tryon Co. the big jobber/wholesaler/dealer in Philadelphia. Of course we also find cards with orders direct from individuals -- Nash Buckingham, H.A. Bartholomew, etc.
Conversely, a big store like H&D Folsom may have had such a quail gun in stock.
Many of the old catalogues mention ordering through your dealer, and if he can't/won't supply your needs, order direct from the factory.