[riddleofsteel]

I used to wonder the same thing. Then I read an article that told about a group of traditional shooters in the western states that followed the mountain men's old ways.
As far as muzzleloaders: They shot mostly .50 cal and above with round balls and greased patches killing deer, bear, small game and elk. Plastic sabots, oil based solvents or detergents strip the seasoning form a barrel and encourage rough bores, rust and hard loading.
A new muzzle loader barrel is like a new cast iron frying pan. It must be seasoned correctly before extensive use and cleaned correctly there after.

1. These guys used animal fat for lube. Bear or hog fat being the favs.
2. They NEVER used any solvent or soap of any kind in thier barrels.
3. Most cleaning was with patches, a soft brush and hot water. Like a properly seasoned cast iron pan the bore takes on a smooth "no-stick" surface that allows for easy cleaning.

I have a T/C Renagade .50 that I replaced the barrel on after reading the article. It has never fired anything but .50 caliber balls with lard lubed patches or spit patches in a pinch. Cleanup is as easy as heating a little water and swabbing the barrel with it until clean. I have never seen rust on a patch out of this barrel and it stays loaded year round. I fire it at least every couple of months which is probably a lot less than the old timers fired thiers.