Um.
I haven't read the 76 pages of discussion here, admittedly.
But how do zombies eat?
There's the 1/10 rule for predator energy, plus zombies only eat brains, which makes zombies even less sustainable. So at most you can have like 1% of the population be zombies, otherwise they'll start starving to death. Also, their organs are pretty crazy. How do they function without all their vital organs?
However! Maybe we can interpret zombieness as some sort of rabies? Also, it decentralizes all the organs, so that even if you get shot in the head, only a few percent of your brain will have died (the rest is spread out throughout your body). This also explains why zombies are so stupid and slow; how can you expect them to walk around when 20% of their liver, kidneys, etc. are failing?
As to energy, I dunno, the virus has developed a 99% efficient fusion reaction that uses a protein only found in human brains.
Anyway in this case you can't really target essential organs (this is how zombies are usually depicted, yes?). Bullets are not as good here, since they are excellent at piercing vital organs but don't actually destroy the entire body. I would suggest some sort of blunt/slash weapon and aiming to cleave the torso in twain.
That's my analysis that I just made up, feel free to ignore it.