What is the best way to clean the inside residue from a breech plug?

Thanks,
Steve

I'm guessing that you're asking about the flash channel. If so I have to use a couple different sized drill bits (I turn them by hand) and a nipple pick for my Triumph.

Torch Tip Cleaner, available at almost any welding supply store, or better stocked hardware.
"Sneak Up" on clearing the flash channel,...and don't force anything,..."turning" a drill bit ENLARGES holes,....
Tip cleaners are DESIGNED to remove carbon fouling,....
thank me later.

GTC

ultrasonic cleaner

Well, if I felt my breech plug face might need cleaning, I alwaus screwed a breech plug scraper on my wiping stick. This would have been on simple flint style breech plugs. Generally speaking I never found them to be that dirty That is if properly maintained.
Postscript,
I clean with tow and tow worm. I find them thorough.

May not be best way for everyone.

Thanks guys for the information!

Steve

After I shoot mine a bunch I pull the plug an nipple and drop them in my ultrasonic cleaner it gets every little bit spick and span.

I soak mine in vinegar, inside a small pill bottle,. Since I never store my MLs with breechplugs attached, I let it sit and soak for a couple days. Pipe cleaners, q-tips and a small safety pin opened up keeps things tidy in there. Afterwards, using the long red straw of my garage carb cleaner, I shoot short sprays of carb cleaner to remove any leftover residue - then let stand and air-dry for another day.

My muzzleloaders are stored in my gun safe with the gun's butt-stock up. That way I'm assured my breechplugs are bone-dry when I install them, prior to range day or hunting day.

I use the bore solvent that I clean the bore with and use a patch and keep rubbing the chamber side with that until clean. If I can't get it clean, I might scrub it with a brass barrel brush. If I can't see through the flash channel, I'll use a nipple prick or a paper clip to poke it through. Then I use a patch with bore solvent and insert my finger nail to clean the threads.