Definitely the dumbest part of World War Z was them handwaving away why the US military couldn't stop the zombies by saying that they used anti-tank ammunition and lacked the preparedness from fighting "brushfire wars:"
- Why would the military forget they have HE and other infantry-defeating rounds?
- Why would a military fighting "brushfire wars" not be prepared to fight an infantry only war?
- When you consider that zombie hordes are a) tightly packed and b) not trying to take cover, you can get some efficient effects from APFSDS spearing multiple guys etc.
- Seriously, no matter how resilient your zombie is, anything above 5.56 will break bones and tear muscle, making them physically incapable of functioning.
- Unless you're pulling an Exmortis or something, no zombies can withstand getting a MOAB dropped on them
