>>64484688 (OP)
Zombies are fictional and the "rules" for how they work don't really make sense, nor are they consistent from one fictional depiction to another. Therefore, like vampires it is hard to say if any given weapon would be "good".
I am assuming that we are going with the type of zombies portrayed in "Night if the Living Dead". Slow, strong, stupid, but nearly immune to any injury other than the destruction of their brain or brain stem.
For that application, a suppressed 22 would be great. Stopping power is irrelevant, only precision and stealth matters. A larger caliber might have more effective range, but sitting in a safe spot and plinking clueless zombies with a suppressed 22 is probably the smartest and most efficient approach. I suppose something like a suppressed pistol caliber carbine in 45 or 9mm with subsonic ammunition might crush through a skull more reliably.
If we are talking 28 Days Later or Left 4 Dead plague zombies where they can run/climb and are basically living humans with advanced rabies the situation is a bit different. You don't need to shoot them in the head. A suppressed weapon would still be advantageous, but ballistic performance matters a lot more because you are trying to wreck organs and knock out a creature that is biologically still human.
I reckon a short barrel suppressed AR in subsonic 300 BLK would be a good choice.
In both scenarios there is the added threat of armed non infected humans fighting over resources where the 22 does leave you a little under-gunned (but not harmless by any means). So overall I'd rather have the suppressed .300 than the 22. Or maybe both.
