Most people on this board may already know better, but make sure when you're hunting on a wet, rainy day that you either keep your muzzleloader level or pointed down while walking to and sitting in your stand. One of the guys in our group had a nice buck right below his stand last Friday evening and when he squeezed the trigger, all that exploded was his 209 primer. Turned out that he had his gun hanging in the stand all day with the muzzle end up. Some of the rain that made it into the barrel must have gotten into the rifling and found its way to the powder.
He learned a big lesson at a big price!