I believe that federal law allows us only 50 pounds of black powder to be stored in our homes.
https://www.atf.gov/explosives/qa/black-powder-subject-regulation-under-federal-explosives-laws.
Does that include substitutes?
No. "substitutes" are "propellants" not "explosives". As an aside; Smokeless or nitro powders for hand loading are also "propellants".
Can I have 50 pounds of bp and 30 pounds of substitutes?
Honestly? The issue of "how much"? Is more closely regulated by an individuals local State, County and City laws and regulation.
Example; (Local for me);
1. I live in a City, they say I can have only 10 pounds (of BP) with no limit of "propellant"
2. A friend lives 1 mile down the road outside of the city, but same county,, he can have 20 pounds
3. Another friend lives 5 miles east, outside the City, different county,, he can have 50 pounds
Can I have more than 50 pounds of different sizes and brands? Can i have 50 pounds of FFg swiss and 50 pounds of FFFg Goex?
Uhm(?) no.
What they all worry about is local "Fire Department issues". Ya know(?) Are ya in an old part of town with houses 15 feet apart? Or are ya in Walden woods with 15 acres between houses? Rural? got a neighbor a 1/2 mile down the road?
A simple call to the local FD Chief will answer all of your questions, the true answer is, it's a local issue for each of us.
p.s.
Seems to be kind of a don’t ask, don’t tell topic, at least in my opinion. Draw attention to yourself and someone, no matter what is legal, you will have an issue.
I suppose, so bob,, if you call the local FD? Use a burner and don't give'm your name!!