[Renegade]

I didn’t know fireworks stores sold bulk black powder. Is that true?

[outpostinmass2]

No,
He purchased fireworks:

http://www.boston.com/metrodesk/2013/04/23/older-bombing-suspect-purchased-fireworks-fireworks-store/1XkVkPaumyROa2kIpwWlCK/story.html