Be very very careful when thinking about using any loads mentioned in Cartridges of the World, especially anything that isn't standard off the shelf stuff that can be readily cross-referenced with other load data (Nosler, Hornady, Speer, Lee, etc.). Many of the loads they show for obsolete cartridges are very hot especially for use in combination guns like double rifles. Butch Searcy is very knowledgeable and so is Dave Davison of CH4D. These guys and others like them have boat loads of knowledge in this area and others relating to firearms. Graeme Wright’s books are excellent and pretty much considered "bibles" of sorts when it comes to reloading for double rifles. Even if Graeme hasn't listed a recommended load in his book he does give one the principles behind load development so you can do it yourself but doing so requires a great deal of patience and attention to safety.
Regards,
Buchseman
