Re-design that. Seriously, not trying to be rude or anything but that design has so many things wrong with it. I really don't see a drill bit end helping it any, maybe a pointed end but not that. Seems like that would slow it down upon hitting the target.

Good luck though.

Edit, also wouldn't it explode on impact not dig into the target? You said it could explode mid-air also creating a shock wave, etc?