Have you ever tried putting the cleaning rod with a brush in a drill? I cleaned up an abused Black powder that way once.
tried that with the wd-40. let it sit over night with the same results. i'll try the h#9 tonight.Plug the bore end at the muzzle, stand it up on the muzzle, fill the bore with Hoppe's #9 or Sweet's 7.62 or your favorite cleaner and let it sit for an hour or two. Then run a brush thru it vigorously. It may have dried cosmoline in there for a 100 years or so...