If you are a handloader... or you know a handloader, a good trick for removing revolver cylinder crud is to take a Magnum piece of brass and run it through the size die -- and then run it through the case mouth flare die. Give it a nice, big (too much?) flare so that it'll just go in to the chamber.
Now lightly tap it all the way in to bottom it in the chamber.
Use a wood dowel from the cylinder face to lightly tap it out.
Repeat as necessary, do all chambers.
The piece of brass is much softer than the cylinder, it won't harm anything, but it becomes a purpose-built "tool" for removing the crud from cylinder. Works very well.
Just don't use the revolvers ejector rod to remove this "tool." You don't need to impart that kind of stress on it or the crane.
Attention Brass rats and other reloaders: I really need .327 Federal Magnum brass, no lot size too small. Tell me what caliber you need and I'll see what I have to swap. PM me and we'll discuss.