Since smokeless powder is chemically a plastic with a large overabundance of nitrate units, pouring the powder into a bucket of water will only prevent it from lighting up while it's wet.
If you pull it down, I vote for either fertilizing your favorite plant friends, or just lighting up the pile outdoors. Be sure it never gets into mischievious hands (like mine when I was a kid).
In all seriousness, I would be quite surprised if you were looking at anything other than cosmetic blemishes. Even true surface corrosion would have to remove a layer of brass almost as thick as a business card to really cause problems (assuming fairly normal starting thicknesses of brass).