Cleaning a muzzleloader is essential to gun longevity, but also accuracy. Black powder is more corrosive, and "dirtier" than standard smokeless powder, so regular cleaning is even more important for your muzzleloader than for your standard gun.
The process for cleaning a muzzleloader is essentially the same as it is for cleaning any other gun. However, there are three tips I can pass on that make the job much easier.
Tip #1 -- Consider the type of powder used:
Certain powders are specifically designed to burn cleaner. Using these powders will make clean up easier without any loss in performance that I can see. Winchester Triple 7 powder and primers are both designed to be cleaner burning. I have been using this powder for a while now, and I recommend it.
Tip #2 -- Use a cleaning solvent specifically designed for black powder:
Regular cleaning oil (like Hoppes #9) will not work to dissolve black powder. You need a solvent specifically designed for black powder. These solvents are generally water based, and many have a citrus scent. They work great to break down black powder. My method is to take out the breech plug, and letting it soak in a bowl of solvent. I then proceed to clean the bore dipping the patch in the solvent-filled bowl.
Tip #3 -- Lubricate the breech plug before screwing it back in:
Taking the breech plug out can be a struggle if it's not lubricated. Lubricant specifically designed for black powder is available. I use this, but I suspect some standard type of lubricant would do.