Granting that gunpowder is shipped as a hazardous material, your out is that it does not explode. It burns, rapidly, in a controlled manner.
Also, loaded ammo is not considered a hazardous material, so far as I know. (Explosives, not political standpoint, doncha know...)
My best advice, I guess, is don't let the danged landlord know. Your self-defense is not his business, anyway. Your well-being is his civil responsibility; is he paying for all new locks? Any previous tenant may well have a key.