@SCAR333,
I would suspect that you could use hunting ammo for self defense, but I would have concerns about bullet performance and how the choice of hunting ammo might be used against me in the criminal and civil trials that would definitely follow!
From what I have read, bullets constructed for varmint hunting tend to expand with "explosive" results. Hunting ammo is designed to penetrate deep and destroy vital organs in game. I would anticipate that any prosecutor looking for a conviction would try to twist these facts into the defendant wanting to inflict a higher degree of damage, and potentially twist a self defense scenario into a stalking and hunting scenario, making the defendant the bad guy.
In a civil trial, if one is launched by either the "victim" of your "self defense" action (or their survivors) will try to paint the blackest picture of you, because you not only assaulted their loved one needlessly, but did so to inflict the most injury and pain by your choice of ammunition. Remember, in our current society, the gang member cherubs from the local boy's choir were on their way home from practice when you ambushed them.
Personally, I would steer away from hunting style ammunition and use either ammo made for self defense or run of the mill every day range ammo that has proven itself reliable. I would not want to make a judgment against me easy to obtain.
Remember, the self defense scenario doesn't stop when you pull the trigger, it is just getting started!