RT/LT. While there may be some who will argue that there's a game advantage to legs, it doesn't fit design theory well-as in how are you going to run the track for the ammo from the right leg to the left arm? This is probably an oversight on the game design (or done for simplicity). I definitely avoid any ammunition in the CT and Head. You can get a crit without a kill, but that ammo crit creates a kill if you've got ammo in the CT or Head.
