After a cold day, like today, I always allow my guns (ML or otherwise) to warm up first. Remove them from the case right away! After cleaning, I generously mop the bore with an oiled patch, happens to be 10W30, but any good oil will do. I think the important thing is that the bore is EXTREMELY clean and dry before it's oiled and put away. I also wipe down the outside steel parts with an oily cloth. When I'm putting it into the gun safe, I try not to touch the steel-I've seen fingerprint rust before on friend's guns. I make sure that all traces of oil are removed before firing again. Some shooters say that petroleum products should never touch the bore but I think that's hogwash-just make sure that the bore is free of oil when it is used again. Muzzleloading guns are able to be treated with what's available, and still work fine, just like in the old days. They made do with what was available, and I'm sure they wouldn't have hesitated to use a petroleum product if one was available. I've never had a problem with rust-but I have had mold grow on wood stocks!