I have a colt CCO with the matte stainless slide. The stainless on the slide has a nasty tendancy to really pick up dirt and grime and fingerprints and smudges and....well... you name it. Cleaning it effectively (like a lot of stainless appliances) has always been a nightmare.
Today, on a whim, whilst cleaning the gun, I decided to try "ZEP Commercial Stainless Steel Cleaner"... The same thing we use on our stainless appliances. It's an oily substance in a spray can. I sprayed a bit on a cleaning rag and went to work. It did a fantastic job! I was shocked. I had tried a bunch of other cleaners and it was always high-work with low-return. This stuff made it look good-as-new.
Figure it might work on any stainless gear folks have out there.