To respond to the above replies....
I don't do anything out the ordinary, other than reloading my other guns. I don't know enough about black powder, but from what you guys have written, it seems to be safe to store a small amount of powder. Powder would be in one of the Powder Flasks purchased from Traditions, and it would most likely be "almost empty".
The powder's original shipping container is a can with a screw-on top as I recall, larger in size than my Flask. The flask is certainly heavier duty than the can.
To 'Doc Hoy': 20 grains of the powder would be "dropped" into the tube on the powder flask, then that small amount would be poured into my Powder Measure. Then I would empty the Powder Measure into just one chamber of the cylinder. For a while I will be using one of the wood stands that holds the gun up on end, making this easy. At some point in the future, I will probably be using a cylinder reloading stand I bought. Regardless, cap(s) will not be placed on the nipple(s) until I'm ready to fire.
'44Dave', I plan to do things exactly as described in the Ruger Old Army manual.
I'd like to do things properly, and have read lots of sometimes contradictory advice about how to do things. Until when/if I find out otherwise, I'll be loading 20 grains of BP, roughly 30 grains of "cream of wheat pellets", followed by a bit of grease and then the ball.