[BenjiWiebe]

Btw, flash powder (at least the pyrotechnic variety as opposed to that used for camera flashes) is actually a primary high explosive.

Primary = easy to activate, doesn't need an explosive initiator. High explosive = detonates rather than deflagrates.

And for bonus points, most flash powder is self-confining in very small quantities. Means a little pile of powder will detonate even if not enclosed.