I have been very successful soaking for a couple of days in a solution composed of 2/3 rds turpintine and 1/3 30 weight nondetergent motor oil. It will remove a lot of rust without removing case color, blueing or patina. For barrels, I use a long plastic trey normally used for wetting wall paper to hold the solution and barrels.

If I do any rubbing, it is never with steel wool. I use copper wool extremely lightly.

Riprap