I use Hoppe's No. 9 solvent. I apply it liberally with a small paintbrush, let it sit for awhile, and brush crud with a brass toothbrush. Repeat as necessary. My air compressor does wonders for small areas that are hard to reach after the solvent loosens things up. The brass toothbrushes are at my local hardware store with the plumbing, specifically, the soldering supplies. I also use bronze wool and small brass scrapers made out of large rifle brass. I flatten the case mouth and it makes a great little scraper for heavy buildups of rust or crud. The brass scraper may leave little streaks of brass, but some No. 9 on a rag wipes it right off. I can apply lotsa 'elbow grease' with my non-ferrous implements with no fear of damaging remaining finishes or natural patina. Cheers!
