i use a secret sauce concoction for cleaning all my bp guns, flntlocks and cartridge. it's too good for me to keep to myself so, here it is, dihydrogen-oxide. the cool thing about it is it's found most everywhere and it's ... free. no shipping, no hazmat, no local-state-fed taxation, either. there's only ONE catch - you gotta use it as soon as possible.
if you drove to the range, woods walk, hunt venue, after yer last bp gun discharge and yer getting ready for that long road trip back to the ranch, just wet down the barrel with something that'll keep the bp residue soft, without promoting corrosion/rust. water soluble oil in a 1:6 mix with dihydrogen-oxide (aka "moose milk") is all that's needed. yep, ya gotta buy that oil, sorry, dunno where to git it free.
oh, and after reaming out the barrel with that sloppy moose milk, leave the ramrod with wet patch nestled in the chamber. OH! and fer you folks with them offshore smokepoles what got them dang "patent breeches", BEFORE running down that patched bore jag, drape a patch over a .32 brush (bronze or nylon, don't matter) and git 'er sloppy moose milk wet and ream out that ante-chamber, THEN proceed with the moose milk patched jag on the bore itself.
back at the ranch, just use plain tepid water to pull out the softened bp residue. goes purty quick, just use patched jags and that secret dihydrogen-oxide stuff. if you have a hooked breech half stock gun, better yet to pull off the barrel and dunk the ignition end in a pail of dihydr ... oh phooey, lemme shorten that to H2O
... and use the patched jag as a hydraulic pump to suck in clean WATER and pump 'er out. when the patching looks *reasonably* clean (it will NEVER get "perfectly clean") send down the drying patches (if you have a patent breech, dry that out first) and then an oily patch fo finish. locks should be pulled, dunked in plain water while ya work on the barrel, then scrubbed out with a toothbrush (no, not yer wife's - made that mistake only once!) rinse off, dry off, wipe down with an oily rag - i use a needle oiler for a *sparse* drop to all moving parts and wipe off any excess oil.
just to be sure all is well with yer beloved muzzleloader, give the barrel a check the next day or two later.
the absolute
KEY to using just plain water for bp residue cleaning is to never allow yer barrel(s) to become hard caked with residue or worse yet get corrosion or rusting. be kind to yer smokepoles and they'll in turn be kind to you. once you've "let a barrel go" then yer forced to drag out all those nasty concoctions and spend a lotta time and elbow grease for a lotta unnecessary work.