removing copper plating from 302 stainless steel removing copper plating from 302 stainless steel redlegs (Agricultural) (OP) 28 Mar 14 08:41 I have some copper plated type 302 spring steel that I need to remove the copper from. I believe that 10% ammonia will work. Can anybody confirm? Any other ideas? Thanks for the help. RE: removing copper plating from 302 stainless steel TomDOT (Materials) 31 Mar 14 15:40 Ammonia should certainly clean the copper, but you may also etch the stainless, or at least disrupt your passivation. The stainless guys probably know a lot more. Instead of just ammonia, I would look at using one of the many firearm bore cleaners - they should have inhibitors to limit the effect on your stainless.