As far as I'm concerned you're not doing the gun any favors by leaving the wood grimy. I've heard both good and bad things about Murphys oil soap but I've personally never used it.
I much prefer a product called Kotton Kleanser which is safe and has been around for years. I usually will start out just applying some with a cloth and use a soft toothbrush for the checkering. If there's still stubborn grime I'll go to 0000 steel wool and a stiffer tooth brush. Mind you I am just cleaning the wood here and oil soaked wood with other problems is a whole different matter.
Jim
