Another consideration here is the factory treats the surface of stainless guns (I can't recall the method or name of the process), and polishing removes whatever the factory applied. I think I have the post bookmarked elsewhere and will edit if I can find it.

Edited to add: "passivation", creates a surface film making the surface more corrosion-resistant.

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Alan
SWCA LM 2023, SWHF 220