Like Rudolfo said, Hoppes #9 will work but I would wipe the nickel surface down with something else after cleaning. Even one of the silicone gun cloths would be good. Because, if left on long enough Hoppes #9 will also remove copper fouling or at least turn it green. So if some of it migrated between the grip and gun surface you could have a problem if left there for a while. I would remove the slide and spray it down with Gun Scrubber after using Hoppes, scrub the burnt on powder with a toothbrush, spray it again with Gun Scrubber, let it dry completely (I use compressed air to speed up the process) and then wipe it down with a silicone cloth. This is easy, quick and I've had good results for years. The only thing with using Gun Scrubber is that it gets cold and can cause the gun to condense moisture afterward. Just make sure it's dry before putting it back in a gun case.