Are you trying to clean the chamber or polish it? I just got my 280 synthetic and am in the process of cleaning the barrel and chamber. As others have mentioned, NEF appears to use a very thick rust preventer on these areas. I have tried brake cleaner and bore cleaner without complete success. I used JB bore paste in the barrel as a last resort, and it appears to be clean. I use a brass jag several sizes larger than the bore , wrapped with a patch, on a pistol cleaning rod, to clean the chamber. The chamber is much cleaner, but not clean yet. I haven't used JBs on the chamber yet , but may have to use it yet. Sorry for the length, hope this helps.