BH209 is not particularly moisture sensitive, meaning it doesn't draw moisture when left out. As the name implies, BH209 isn't intended to be used in a muzzleloader that doesn't use a 209 shotshell primer. I also tend to leave my inline muzzleloader outside so that it is at ambient temperature when I leave. The exception is when it is wet. I bring it inside to dry out, mostly to prevent rust and to clean my scope lenses.
