Went straight to horses mouth and called smith. They said no problems with hoppes ,just use as directed. Do not soak gun over night. No rash of damaged finishes. This mirrors my experience with my newer 57 over the last year or so. I will keep using it like I have for the past 45 years. Incidentally, he said they did change blue about 20 years ago due to regulations but that would be true of all manufacturers.(epa stuff)