Now I'm starting to wonder if it might actually be more effective than the rubber 9mm rounds. Certainly fits the less lethal requirement, and damn they do hurt. Doesn't put them down to the point they can't run away though if you aim center mass which is what OP was wanting them to do. I'd imagine solid face shots would stop any charging at you pretty well though.
After that suggestion, I just want a full auto paintball gun for s***s and giggles. ANYTHING that spits projectiles in full auto sounds fun.