The muzzleloader season in northern Minnesota can be anything from cold, wet conditions to dry and subzero temperatures, all in the same week. I learned the hard way, if its cold and damp that day, even if it don't rain, fire it and clean it. The day after such a day it dropped from above 32f to -10, out walks a deer saying kill me and laughs at me as I fire off three caps trying to get that gun to go off. I used to store my gun in the garage loaded all season with the cap off, now I let the weather determine if its okay to do so. I have no problem leaving a load in my muzzleloader for short periods and I'm a corrosion freak, check the damn thing weekly now, even in storage, found some rust in my sons cabelas hawken once after 6 weeks of storage, I had cleaned it, not him. Its okay to leave a load in there for short periods but moisture in any form will create a problem, use discretion. Oh yeah, the gun did fire when I got home, with a long sizzle and a kaboom just like my season. I like my venison frying in a pan, not running around my back yard eating my wife's shrubs all winter.