You can dry out black, not to sure about the subs, the only powder you might use that is not hygroscopic to some extent is the new Blackhorn 209. It is expensive but it is also the most consistent tightest grouping powder if you find a load the rifle likes and can shoot well enough to tell the difference. I kept my powders in a dehumidified gun safe till in started using BH209 and that worked well for the ones like 777 and pyrodex that take a period of time to absorb any moisture, keeping them sealed when you are not shooting helpsalso. A lot can depend on the area you are in and the amount of humidity. Lee