Decarbonization fluid to clean muzzleloader??

[Erwan]

If I remember my high school chemistry caustic soda is sodium hydroxide also called lye which is a very strong base.
Not near my guns thank you

Sure that the caustic soda is a strong base and could be dangerous if handled without care...
The big advantage is that it's absolutely soluble in the water, so this can be used like simple soda lye, like the painters used to wash the paints before to make a new paint over the old one after rinsing...
I did wash four or five old barrels with very hard and old calamine in the chambers, in that case no other solution : soda lye or scraping with a metal tool.... I prefer soda than a drill bit softened with a stone to scrape the chambers...
This is dangerous or very bad for the wood, oil and varnish (also very diluted) but not at all for the steel...
Try this on some piece of old steel more than dirty, rinse generously, dry and reoil after the operation (it takes a bit time) and tell me what...

 

[Stantheman86]

I have the bore of an Armisport Richmond full of Murphys and soapy water. In a couple hours I'll dump it out into the outside dirt and clean with Ballistol patches. Pump patch soaked with Eezox down the pipe to protect everything from rusting. I don't even take anything apart, easy peasy.

Let the soap/Murphys/water etc do the work , my main concerns are the breech area and flash channel. It's messy but I do it outside.

There's no need to use aggressive or caustic agents to clean blackpowder or subs.

People back in the day used hot water, coffee ground water or whatever was laying around that was wet.