I've heard household bleach and I've also heard lemon's can be used. 0000 steel wood applied with oil, to get through the grime, then degreased. Then the bleach (or lemon juice) applied (barrels plugged) and rubbed with the same 0000 steel wool. Then washed or boiled in very hot water. Then hot baking soda wash applied liberally to neutralize the acid, scrubbed with a brush. Finally rubbed over and over with ballistol with multiple rags. Then a good wax. Ok. I've tried the above on a junker and amazingly it came out pretty well. Neat little project to do at home and it truly doesn't take long.
