Some of the reason that Pyrodex is more available than Black Powder IS the law.
Black Powder is an EXPLOSIVE,way different HazMat requirements,local laws/rules as far as amount/storage.Get a copy of the Haz Mat Rules for bulk storage. .
Where as Pyrodex is a PROPELLANT!!!!!! totally different HazMat/storage/local rules.
Go to your local Gun Shop/Shooting Supplier,,lots of Pyrodex on the shelf compared to Black Powder,,the BP is out back, away from humans in a explosion proof building made of reinforced concret,rebar and a roof designed to blow up and away to redirect the blast,if a certain amount is kept in it.
Ill shoot till it gets to expensive,,then eat less,shoot less or figure out how they did it in the "old" days,,,during my childhood,,ha ha ha ha ha. Lead is in the ground and BP is in your basic Chemisty book!!!!
Remember: Work like you dont need the money,love like you've never been hurt,and dance like you do when nobody is watching.