The biggest issue you would have with using a 9mm is finding a good bullet thats not going to expand too fast to get the penetration you are looking for. Ive thought about giving it a go with my .40, waiting for a 30 yard or less shot, but the biggest reason I havent tried it has been lack of a good bullet. The big, hollow points like Hydrashoks, etc are made to expand quickly and not over penetrate. They design them that way because they are personal defense loads, and you dont want the bullet going through the attacker and then blowing through walls, etc putting others in the building at more risk. On the other hand, you dont want an FMJ that just punches a hole through, doesnt expand much and cause the shock you are looking for. I have throught of maybe taking some FMJs and using a dremel tool to slice an X in the tip of the jacket, which should hold the bullet together, but still allow it to expand. I would want to test them on some ballistic geletain first to see what they do though. Maybe one of these days.