I cleaned up an old muzzle loader a few months ago with an acetone bath.
Soaking in acetone. I use a sheet of tinfoil over the top to seal the bath container. In this case the container is a plastic window box for flowers. For shorter box lock stocks I use an disposable aluminum turkey baking pan.
The stock drying out, sorry I dont have a better photo.
The gun put back together and awaiting some new percussion nipples.
Ive done a bunch of guns this way and Im always happy with the results. However, I am not a perfectionist. Especially when I know that come rain, sleet or snow Ill be taking the gun into the field.
Steve