When shooting to kill with my 5.56; I prefer to send jacketed soft points down range. The expansion will easily stand toe to toe with any hollow point or ballistic tip, while allowing more penetration. Personally I have shied away from buying any hollows for rifles. ( I just feel there are better options available for the priced per round of hollows)
After buying my AR, I picked up an impressive variety of different rounds in different weights. I suggest you do the same. If your LGS does not carry any JSP in 5.56, look online you will not be disapointed dealing with these folks.
http://http://www.ammunitiontogo.com/ look into their DRS reloads, I have never had a problem with any of there ammo, and at the PPR i would like to think they are one of the best deals currently available for brass cased ammo.