Here is the image from the wiki:
You can see that AP SX has the highest pen, but the problem is that it only does 35 damage. This means that even if you do pen the helmet on the first shot, you will not one tap because you will lose at least 1 damage going through a helmet even while penetrating it. With FMJ SX or Subsonic SX you will pen most helmets AND one shot kill them, so in most cases AP SX is worse for shooting heads.
AP SX is also far more expensive, so I don't suggest using it. Even against level 5 armor folks with visors I would still rather run FMJ SX.
So the next decision is, do we use FMJ SX or Subsonic SX? The neat part about the subsonic is that it has a massive -22 recoil % which is a massive difference; See below (No recoil control used).
FMJ SX RECOIL (40 PEN, 43 DMG)
Subsonic SX RECOIL (36 PEN, 45 DMG)
As you can see the subsonic is significantly better, at the cost of 4 penetration. I'm leaning towards subsonic because of this; but this falls down to personal preference. Either option in my opinion is better than AP SX which actually ADDS 10 recoil:
AP SX (53 PEN, 35 DMG)
Thoughts on which ammo to use?
