One of the prolems with gun store owners selling black powder is that they simply are not very good salesmen. The LAW prohibits them from displaying the Black Powder openly on their shelves.
However, it does not prohibit advertising the fact that you carry and sell Black powder. A simple poster or sign in your store that tells customers that BP is available, and to ASK FOR IT will sell lots of black powder! And, it doesn't take much of a genius to contact the NMLRA site, get a list of Charter clubs in a 100 mile radius, and send out photocopied notices to each club telling them that you have Black powder for sale, and how to arrange to buy it from you.
I know clubs willing to pay the license fees for the store owner, and even offer their range property to store the black Powder in a properly constructed "bunker" for the local store.
For gun store in "strip malls", where they can't satisfy the requirement that the storage facility be located 300 feet from an occupied residence, This is a terrific way to "solve" that problem. Delivery of retail sales to customers is arranged to occur on certain days of the week when the powder can be transported to the store's temporary storage facility, but not kept there overnite.
With the difficulty that everyone has dealing with these unnecessary Federal Regulations in order to have a LOCAL source of black powder, any dealer with a retail gun store would be way ahead by making deals with local gun clubs, so that he has a place to store powder properly, and the club members have a source of BP locally.
The dealer not only makes a small profit on the sale of the powder, but he also then has a steady clientele coming to his store for other items. :hmm: