In the long term, there is no such thing as hoarding.
That is, unless you buy powder that you never use or simply throw away.
Think about it rationally. For the sake of argument, let's say each reloader goes through 100 lb of powder per year. Also for the sake of argument, let's say the entire industry produces 200 lb of powder per year.
Reloader #1 goes to the local gun shop one day and sees 200 lbs of powder on the shelf. Thinking about the last time he was left staring forlornly at empty shelves, he buys all 200 lbs.
Reloader #2 comes in the following day and sees that all the shelves are empty! That jerk reloader #1 is a hoarder!
Except that reloader #1, by buying twice what he needed, has effectively removed himself from the powder market for the next two years. Unless he buys powder that he subsequently throws out, the overall supply of powder is not affected by him and people like him in the long term.
All 'hoarding' can do is cause local outages in the short term.