So. A bunch of years ago I bought a No. 4 Mk. 2 because the numbers matched, but it sat in the back of the safe ever since. Pulled it out this week to clean it up and maybe shoot it a bit over the Christmas-New Year break. (Yup, I should have cleaned it up when I first bought it but was extremely busy at the time (excuses, excuses) and anyway that's water over the dam).

The exterior actually looks to be in good-excellent shape. The bore is a different story.

Based on advice from somebody on this site I bought a bottle of Patch-Out liquid because it seemed possible the barrel could have some copper fouling; in any case better safe than sorry.

Day #1: Ran a wet patch through and it came out bright darkish blue. Kept running patches through (about 15) and although decreasingly bright were still distinctly blue. Switched to nylon bore brush; back and forth five times, then followed with a patch wet with Patch-Out. O.M.G. The patch was absolutely black--almost muddy. Not good.

Fifteen more wet patches through and although no longer muddy, still had some blue color. Let's try the nylon brush again...EXACTLY the same result as before: muddy black patch with blue at the edges. This is the place for a well-known military technical acronym: C. R. A. P.

Repeat cycle three more times; same results each time.

Night #1: Run patch well soaked with Patch-Out and let it soak overnight (about nine hours).

Day #2: Replay of Day #1, except in between running wet patches 1) ran the nylon brush through five times each way--still got a muddy black/blue wet patch out right after. 2) After another iteration of wet patches, switched to a brass brush--got a REALLY muddy black wet patch out right after. Repeated wet patches--brass brush routine twice more, with EXACTLY the same result each time: muddy black wet patch right after.

Night #2: Well-soaked patch through to soak overnight again.

Day #3: Exact repeat of Day #2, except used only brass brush each time in between wet patches.

Night #3: TWO well-soaked patches to soak for 24 hours.

Night #4: 24 hours after last wetting with Patch-Out, ZERO change from the very first time I ran a patch through this barrel. Bright blue if Patch-Out only, and muddy black with dark blue edges after brass brush runs. I've now used almost half a bottle of Patch-Out and way over a hundred patches, so I'm out of ideas.

I don't have a borescope, and don't see any point posting pics of the patches or the towels used to wipe down the cleaning rod after each pass (although I can if you'll think they'll help).

I acknowledge the distinct possibility of operator error, so am I doing something silly here? I've cleaned a reasonable number of rifle and pistol barrels over the decades, and even the range rifles they gave us pilots on range day were not even close to this dirty.

You guys are the Subject Matter Experts, so I'm all ears (actually, eyes).
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