Good job with the photos in post #47.
I just ran a coat hanger down the barrel and it's not loaded. Also, it filled with grease all but the end 5". It's possible that the bore is clean under all that grease!
There isn't any oder From the grease. I would expect it to smell like petroleum. If it wasn't oil based you would think it would be dried and solid.
While I have not actually encountered an old muzzleloader with the barrel full of grease, I have read about it. When the gun or rifle was expected to be put away for a relatively longer duration, it was evidently common practice to plug the touch-hole and fill the (clean) bore with melted tallow, which would solidify when it cooled. This sealed the bore to protect it from rust.
Getting the tallow out was a less onerous chore than you might think… They would stand the firearm near the wood stove until the barrel had just warmed up, but not hot enough to completely liquify the tallow. They would then tip the gun muzzle down, over a container of some sort, and the tallow would slide out in one semi-solid column. You then wipe the bore as you normally would.
I will say I have not tried this; it’s just something I read, and I can’t remember where. Maybe in an old issue of Muzzle Blasts. It sounded logical to me.
I do have some experience working with tallow, though. It has some odor, but not much, and it is not unpleasant. Clean, properly rendered tallow keeps for a long time. I have some Old Zip patch lube from Dixie that I got in the 1990’s that is still good, with no rancid smell. Old Zip was an 80/20 blend of mutton tallow and beeswax.
Anyway, I can’t say that the subject gun’s barrel has tallow in it, but it might.
Please keep us informed of your progress in conserving this interesting old gun.
Best regards,
Notchy Bob