I use a cleaner degreaser from the local dollar store called L.A.s totally awesome. 4parts water to 1 part degreaser .

After cleaning brown parts try Navel Jelly to remove the brown then buff up with an old carding wheel. Results should look dull gray. Not new but not brown and not a lot of work.

Mark

https://www.gunsinternational.com/marksbornagainbirdgunsllc-.cfm

DON'T FEED THE TROLLS !