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I've noticed a lot of bores have - discoloration, for lack of the correct term - at the area at the end of the chamber/start of the forcing cone where the shell expands/opens up.

The rest of the bores appear shiny & smooth (depending on how clean they are...) but the discolored area appears the same regardless of which end you look through.

Q: What is the discoloration and is it potentially harmful to the bores? Is it normal and I'm overly concerned?

I suspect it's residue from the shells opening or maybe powder/primer soot - I've spent some time on mine with a stiff bristle brush (plastic) and some solvent but it remains.

Thanks

Member Joined: 25 Jul 2006 Posts: 781

It may be plastic residue from wads. Get a bronze bore brush and one of the newer bore cleaning solvents. Chuck your rod with the bore brush on it in a hand drill, spray in solvent and fire up the drill. Polish the whole length of the barrel. Wipe with swab....you'll be shocked at the amount of crud. Repeat the process until the swab comes out clean after a cycle of brushing.

If after one good effort the swab comes out clean but the bore still looks bad then what you might have is what is referred to as "frosting" of the bores. Early primers left corrosive residue and this it the precursor to pitting. It's usually right in front of the chambers...

Jeff

Carburator cleaner removes plastic wad residue very nicely. Be sure to wipe the bore clean and follow up with some oil. Carb cleaner removes oil too.

givin it was made pre-1940, I'll bet there's the pre-pits from primers...

I'll give it the power wash when I get a chance - thanks Men

Member Joined: 25 Jul 2006 Posts: 781

Sprocket,

It's probably both. A little frosting or pitting will reall grab and hang on to plastic from the wads.

Jeff