Grinding it into powder to get a fine grain is the dangerous part as BP will ignite from concussion or impact.
Flash
Burdett & Son, located on Texas ave. Their number is (979) 695-2807. I just had their card out giving some info to one of my coworkers. Great folks. If they don't have something on hand they're happy to order it for you.
I think what I have gotten from them in the past is fffG in 1 lb cans.