Whoa, crazy idea... Just reading the title, rocket propelled...
What if you had a rocket propelled projectile (ala estes) that sent up a quartered cylinder full of BBs/powder... The entire projectile could be parachuted down at a safe velocity (temperature would probably be a bigger issue). The deployment charge could be used to trigger both the release of the BBs as well as the parachute. At altitude, the BBs can probably spread out enough to give a fair 'blast radius' once the BBs reach the ground. To prevent direct hits, the launcher can have a safety gimbal that would prevent firing below 45 degrees or something.
Sort of like airburst artillery...
Crazy, probably stupid and unsafe, but different. Has anyone considered this before?
Vita, Passione e Pistole