The Posse has given renewed thought of late to the (impending?) zombie apocalypse, specifically which firearm is best.
When we first visited the topic, discussion was vigorous and animated.
Since then, I've watched a lot more zombie movies, and even consulted the Zombie Survival Guide (while amusing in places,the book does have some serious deficiencies, particularly in the discussion of the AR-15).
Anyhow, after four years of review, I think that the ideal cartridge is the humble .22 long rifle. Zombies tend not to use cover, to be slow moving and incapable of climbing ladders. A tree-house perch with a couple 500-round boxes of .22 would pretty much see off even the most severe outbreak.
Remember, the head shot is key. Yes, massive trauma can slow them down, but really what we need is something handy, easy to carry, and accurate. At the same time, minimal recoil and noise is definately a plus. Finally, you can carry thousands of rounds in a handbag, making ammo supply a breeze.
That fancy 9mm won't do much good if it runs out of bullets.
[Okay, so the movie f/x guys aren't going to be busting down my door any time soon. Still, the ketchup/steak sauce combo looks almost real. If you squint. What I need is one of those cool prosthetic hands with bones sticking out of the wrist. But I digress...]
Given the ongoing ammo shortage, this is not an idle consideration. Happily, the .22 remains widely available.
If it comes down to pistol work, a light autoloader would be excellent for the head-shot plinking that this kind of operation would require. Interoperability - being able to use the same caliber for rifle and pistol work - is a good thing.
Of course, if the zombies turn out to be hyperfast "28 Days Later" types, I revert to my earlier comments.