I would never shoot lower than what the bow manufacturer states in the owners manual. with that said the general idea is 350 grain arrows @ 70lbs. I personally would not go much below 380 grains for hunting deer size animals or smaller.I think 400-450 grains is a great range to be in out of most setups today if you are shooting 65 to 70 lbs.I agree with the others, I like a little heavier head for FOC balance & extra KE....125 is ideal in my opinion and if you match your shafts up correctly in the charts most hunting shafts will put you in that range as well.

Good Luck