Where I live, you need a 'permit' to purchase powder, caps, primers, roundball etc. You do not need a 'permit' to possess them.
So, I just stock up on these items. I do not believe that they will come after BP stuff, at least not in the near future. However, the 'permit' can be revoked for almost any reason, by your local Chief of law enforcement. Lucky for me, mine is decent and does not mess with people.