Yeah, I think headshots are pretty cheap, since half the time it dosen't even look like you've hit them in the actual head.
I've recently found two good places to snipe:
1.Fault Line/Subterranean(Spelling?)-
On the little ledge in the corner of the main area(Place where the magmaul and battlehammer is. To reach it either use the jump pad and push yourself to the right, or jump form the ledge that the jump pad takes you to.
2. Harvester-
After taking a jump pad to the second story you'll notice the two pillars. Take the other jump pad and try and move yourself to fall onto it. This may take some practice as its hard to stay on.
ps: For those who don't know (though you probably do), their is a Double damage power-up at the bottom of Fuel Stack. I only discovered it a month ago!
Black
Name: Chris
FC: 3138-8446-5805