Note: Fundamental to our considerations here is the stipulation that Max Brooks is an idiot.
As stated earlier, what you want for a zombie survival weapon depends almost entirely on the situation as you believe it will unfold. Before we can reclaim the world from walking corpses, we need to survive their reanimation. This will not be simple. In all likelihood, a very, very large number of people will die in a hurry if the dead begin to walk.
How many people die, how quickly they join the ranks of the living dead, and what ramifications their demises (or lack of demises) have depend on a few things, not the least of which is speed of infection.
There are really three possible outcomes here, though there's a lot of room for fudging specifics. This could go down quickly, slowly, or at an average pace.
All three have their own particulars, and none of them are nice and fuzzy. What you'll need out of your tools will be radically different from one hypothetical to the next, however, so we'll need to take time to consider them.
SLOW BURN
In this situation, the dead don't all begin getting back up at once. This would seem to be incredibly unlikely, given that the one common trait of all zombie media is God, Chance or Impersonal Existence flipping some kind of switch that puts life and death as we know them directly on their asses. Governmental machinery clanks to life. Martial law is likely not only to be enforced but to have significant resources committed to it by the time control schemes around the world finally collapse. Whether governments (specifically the New Haven government, Connecticut state government and the federal government in our case here) manage to remove people from high-density areas and isolate infection or whether they do little more than crush the individual right to self-defense and ensure that Happy Meals are compacted into pleasantly accessible packaging for the devouring dead is up to personal interpretation.
If police action during Hurricane Katrina is any indicator, control machinery will be all too happy to set us up as a buffet. And I've never seen state government in Connecticut do anything without spectacular amounts of waste and an unshakable dedication to failure.
In this situation, we are much more likely than not going to find ourselves contending not only with shambling death, but human beings as well. In terms of gear selection it's the least interesting case, because we're already all too well-versed in which methods most efficiently murder other people through application of industry and engineering.
Not everyone is going to want to play nicely. The AR/Glock drone will have his day, and will more than likely be shot dead along with a hell of a lot of other people as North America descends violently into chaos.
It is worth considering that, given a little time to leverage against the tide of flesh, the awesome might of the American military (specifically of American armor, which would serve undeniable purpose in the anti-zombie role until fuel ran out), could be recalled and concentrated at critical points of infection. But if the present government can't develop an exit strategy without imminent home-front holocaust, what reason have we to believe that the feds could do it under pressure and on a radically different timetable?
It is also worth considering that certain measures could be taken to check the spread of infection before it grew beyond local containment - cutting off New York City's bridge and tunnel arteries as a prelude to some kind of drastic sterilization could, properly timed, do much to halt Northeastern plague propagation. But this supposes a staggering loss of human life as a matter of course, and is too heartlessly logical a decision to be expected of human minds.
But in a slow collapse, panics, epidemics, famines and droughts will all have the first word. They'll also have the last, and all government exertions will be either aimed at mitigating or preventing them through use of force. Unless the feds simply disappear one day, leaving the Capitol empty, gone off into a mineshaft or a bunker complex with concubines and bottles of scotch, sealed up until there are once again subjects to rule over topside. Or until the dead can be taught to panic, and thus, to vote.
The primary need will be to successfully negotiate human obstacles before coping with the environment. In this respect, we must bow to the awe and grandeur of truly brilliant minds: ARFCOM posters. An AR in .223 is just about ideal, with a Glock or some other polymer wonder in 9mm or .40 S&W for backup. Unless your survival strategy involves doing public relations work from long distance, in which case something bigger might do (say, any old sporting rifle in the Big Four chamberings).
My take is that this last approach would not meet with dazzling success. The arm of government is long, and determined. You avoid it at your own peril in the best of times, and the zombocalypse would clearly not be one of those.
