I don't believe in the seasoned bore thing and treat my ml's just like any other fire arm except I use water and dish soap for the original cleaning in a bucket. I wash out all the fouling with a patch or two followed by some dry patches until they come out white. I then run a real wet patch with regular gun solvent thru it and scrub with a bore brush. I put it back in the bucket and wash all that out and again dry with patches. I stand the barrel up muzzle down in a corner for a couple of hours to dry and polish the bore with some more new patches. Then I run an patch with gun oil down it a few times.

Before I load it next time I run denatured alcohol patches thru it to get the oil out and dry it with dry patches. Load her up and she's ready to go.

I don't like bore butter in my guns. I use criso for lube but even that leaves some heavy fouling sticking to the bore. I get this fouling sticking to the bore even with a spit patch so I am somewhat certain that it's coming from the powder itself. I have only used Goex so I don't know if other powders do it as well. I really kind of feel it's the graphite in black powder.