um...i'm sure something bad will come out of this post, but my friend owned a lot of fireworks...mostly legal stuff like sparklers, but he also had m80s, bottle rockets, and some other piddly stuff. For whatever reason, we decided to get some pipe from the hardware store and some caps. We stuffed it with crushed sparklers and some stuff from a fountain (i think) and sealed it off. We lit it and i swear it was twice the sound of a 1/4 stick of dynamite. He did different variations all the time and showed me little "landmine" holes in the ground from his experiments, but i think he's stopped doing all this (hopefully).
The point of this post: you don't necessarily need potent explosives to make an impact. If you highly compress anything explosive, it will do you just as well.
-=bmacd=-