I haven’t tried anything, but I will.Have you tried some 80-90% alcohol or hoppe‘s with a nylon bristle brush or old toot brush? Looks like what said minorcan said. Since it appears to be stainless this will not hurt the finish.
ya I don’t want a shiny one. I’ve thought about sending it back to colt, but not sure what they are doing right nowTry bronze wool and a lubricant.
Take the gun apart, and disassemble the slide and removed the grip safety. Soak them heavily in a lubricant (gun oil, CLP, etc). Allow time for the lubricant to penetrate the oxidation. Then use bronze wool to rub the oxidation off. Repeat until the oxidation is removed to your liking.
I do not know how this will affect the matte finish, however. You may end up with a brighter slide.
Another option - And I don't recommend it, given the finish and where the rust is located - use Mother's Mag polish. I don't recommend this because you'll like end up with a very shiny slide when you are done.
It was like this out of the box, not due to carrying it or dirty handsPart the problem with brushed or bead blasted metal is it hangs on the stains of every kind . Dirt for your hands , maybe certain chemicals used during cleaning or lube . With a couple months of carry time could you have missed what happen or built up over time .