With all my guns I have always used Sweets Solvent and Shooter's Choice Bore Cleaner... Run a brush up the barrel breech end first with the sweets and let that sit for about 15 minutes to soak in and break away any remnants. Dry it with patches until they are clean. Use a clean patch every time. Yeah you go through patches.... Then do the same thing with the Shooter's Choice. It is the same process I used in the military. We shot our long guns so much we had to. Good Luck!

After a day of shooting, I usually spray a good amount of windex down the barrel. The ammonia in it does a great job of neutralizing the salts that cause corrosion and its looses stuff up. I then soak a 12 guage brush (I'm shooting a .50 Caliber ML) in Hoppes #9 and run that through a few times. After that, I run a couple of patches through again with the Hoppes #9 until they stop coming out black. I'll then run through two patches with oil, two dry patches, and then a patch with TC bore butter.

I've had my muzzleloader for some number of years now and have used it in pretty horrid environmental conditions (rain, snow, wind), and the barrel has remained pristine.