By the way, muzzleloading weapons are still evolving. Many use a "209"(shotgun shell-type) primer for ignition, and a few are even designed to fire modern smokeless powder (NEVER mix or substitute modern smokeless powder for black powder/pyrodex!). Because of my work schedule (and hunting seasons), I hunt more with these weapons than anything else. I use the modern, more reliable muzzleloaders because I can't afford to come home empty-handed!
Black powder firearms are particularly susceptible to rust and corrosion. It takes a bit more time and effort to clean a Muzzleloader/black powder gun, but for me the extra effort is well worth the reward.
NOTE: I'm pressed for time, but I'll try to add a few more pics to this ible soon.
Step 1: Disassembly
Begin disassembly. Tear it down as far as you can. You may need a manual or diagram. Don't do anything that you can't undo!
1)Remove the barrel.
2)Remove the breechplug (if possible), and primer-nipple.
3)If it's really dirty/rusted, remove stock and trigger assembly.