Another pretty easy way to kill hunters:
All you Halo freaks out there will remember in Halo:PC & CE you could simply do a little stroll to the left then shoot the hunter it is orange spot to kill it. Well that tactic hasn't completely vanished. If you get your timing PERFECT then you can simply stroll to the side and fill the orange zone with lead (preferably, lead is better than plasma) sustain fire for a short while. After doing this 1-3 times the hunter will be dead. This is especially effective with a sniper rifle. DW Smgs or Magnums.
Alternate way to killing hunters:
Simply find a fixed turret, the human ones are best and give them a body full of it they will die INCREDIBLY fast. A good place to do this is near the beginning of "Outskirts".
When they are approaching (but not charging at you) you can simply fire a shot into their orange stomach and you will kill them with a shot each in easy.