The reason the military doesn't use Hydra Shock bullets is because they are against the Hague and Geneva Conventions. (Which if memory serves, the US military abides by but did not sign.) It is very similar to a hollow point just alittle more powerful and alittle different. The Hydra Shock is a really mean bullet when it hits tissue fibers. Not quite as tidy as Ball ammunition. Basically war is still, "a gentlemen's" argument, if you will. It's ok to use flame warfare but not expanding ammunition. Actually if you're interested, many people think using a M2 (.50 cal MG) against personnel is a crime since the 12.7x99 BMG round started life as an anti-tank round during WW I. Sorry, got alittle off track.
That is why the military doesn't use expanding ammunition, it against the Geneva and Hague Geneva Conventions.
whew, Leo