stinkbelly,

My first impression when I read your post was as Cayugad's why would you leave it capped? But, after to reading it a couple times it became clear to me and Tahquamenonwhat your concern was.

I think Tahquamenonprovided an excellent answer. Taking the muzzle protection off is important for the barrel to breath.

Moisture is a big concern, sub powders tend to draw moisture rather well. If there is enough moisture in the air to cause a concern - dump the load and start over. I personally leave my ML's loaded forextended periods of time, coming home from hunting, if the gun rides in the truck I will not heat the truck to a really warm comfortable cabin temp. It will remain cool if the outside temp warrants this. When it gets home, if I am going to use the next day it goes in the unheated garage overnight, or if the temp is really cold it remains in the truck. At hunting camp it will remain at the ambient temp by leaving it overnight in the truck.

Rainy wet days - that is where you will really need to make a decision because the air is so damp - the powder will absorb X amount of moisture no matter what. Safe is better than sorry. Time and experiance are and will be your best guide.

Good luck