For touch-ups or smaller parts, the "cream" formula of Brownell's "Oxpho Blue" works great; it is almost the consistency of syrup, so it clings to round surfaces better than a more viscous liquid. I found it works best in multiple applications and with the item heated with a heat gun.

Longest barrel I did was 6" on a blackpowder boot pistol and that came out amazingly well -- but I have not tried it on anything bigger.

Good luck.

Old No7

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