Frost said:
Choice of caliber and weapon platform has been discussed at length on the dedicated Zombie forums.
The general recommendation is a high capacity 9mm handgun and an AR in .223.
My zombie preparedness focuses upon the concept of "turtling" or bunkering.
Using a .22 for aimed headshots from a static, supported firing position in an elevated structure with absolutely zero zombie access (i.e. using a retractable rope-ladder from a 2nd floor window or balcony where all stairs have been axed to pieces) should suffice for, considering their lack of thought processes and basic stimuli/response behaviors, self-mobile reactive targets.
An animal that you are shooting at can move quickly and will likely require a larger caliber to damage their central nervous system sufficiently to not be a threat. You may also need the larger, faster calibers to penetrate any cover this animal takes.
The same is true of people that are living.
A zombie, by any real study, is simply a walking pepper-popper target where only a headshot will make it go down.
It won't be moving quickly.
It won't be taking cover.
It won't be returning fire.
Get behind solid cover. Get elevation. Take slow, well-aimed shots.
It's the end of the world. You have nothing but time.
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If I am in the Zombie Apocalypse and ever have to leave my bunker to resupply I will not be taking a .22
I will be taking an AK.
I don't expect to magically be the only person on Earth to survive a cavalcade of Category 4 Hurricanes, gangbang orgy of F-5 Tornados or the Armagideon of dead people having 5% of their brain reanimated giving them just enough capacity to wander around biting things that make noise or movement. I expect to encounter plenty of other survivors.
Most of these survivors will be hungry, scared and may have passed that thin boundary of "It's the end of the world and my actions have no consequences..."
Given any protracted failure of society there will be a cause to have combat arms to use against your fellow living, breathing, sentient Man.
Given a zombie event, you're not going to need to waste your expensive, heavy, super-effective-against-the-living Hornady TAP or Gold Dot Jacketed Hollow Points on a walking pile of necrotic cannibalism. You
can. But why?
Those 20,000 rounds of Federal .22 Long Rifle I mentioned purchasing... I purchased them at the same time. $200 + Wal-Mart = enough .22 ammo to thin zombie herds for a good while. Ammo prices have increased in the past three years, however, but that doesn't negate the value of having a good chunk of inexpensive, "puny" caliber ammo on hand.
If I need to keep land pirates away from my house that's why I have body armor, AKs and ARs.
If it's a sea of the undead it will be my lounge chair, a window, Ruger Mk III and Ruger 10/22.