Dr.Richtofen Jnr wrote:

 

At what round do you think zombies become terminators? (thankfully unarmed ones!) i think its about 28-32.
After that you can double the zombies body weight with lead and they still steam towards you . I wonder if a zombie perk
machine becomes available to them as they spawn at these higher rounds,i bet its called schwarzenschnapps.

zombie health increases by x1.1 every round so you do the math

115

40

Sounds weird because zombies health increase anyways

In W@W, i found them to be Arnold when it got to round 36.
In BO's...they go all metal on me by round 30. I find W@W zombie to be easier to kill instead of those in BO's. Probably b/c in W@W the only thing you really had to worry about was getting swarmed like hell or having no ammo and dogs kill all 3 of your team mate and your stuck with 10 dogs trying to kill you.
In Bo's...you have perk stealing monkeys and a gun stealing scientist. So yeah, no doubt about it, BO zombies are harder...but not as much.