Horsefly
What I really wanted to convey is that the residue of burnt blackpowder (granted with moisture) is corrosive. Even today I believe it to be true. If I shoot my muzzleloaders with non corrosive primers and let it sit it will rust the steel. I have a rolling block sporter in 40-65 and it is a BP only gun for me. Clean up is a snap with TC #13 solvent (similiar to Dale's Speed Juice). But, I still like to take it down from time to time to give it a good complete cleaning inside and out. Thats something the "new" Browning/Winchester 1885's make difficult.