BreakFree CLP works wonders here, dissolving the current baked on crud, and then stopping any future crud from baking on. Shoot the system 'wet', meaning spray it on the gas rings/pistons/mag tube, whatever, and don't wipe it off. Don't go overboard of course, but leave it looking wet, IYKWIM.
Then, a single swipe with a rag removes ALL the powder residue. That's it. One swipe. No steel wool or brushes or soaking or solvents or scraping. You will not be disappointed. I've not seen any other lube or solvent do this.