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Zombie Nation Tips & Tactics

Zombie Headshots: It’s a Matter of Physics and Caliber Selection

by Patrick Sweeney   |  March 1st, 2012 33
WalkingDead-ColtPyhonFence

You may not get a point-blank shot, like in this clip from "The Walking Dead," but zombie headshots are still a vital part of surviving the horde.

Consider the skull: an armored, curved structure with stiffening ribs and internal support structures located on top, where it can swivel and use detection sensors to locate dangers. Sort of like the turret on a T-72 tanks, but with more forehead.

It is that way for the same reasons the Soviets designed their tanks the way they did: protection. As we discuss this, also keep in mind a technical term: angle of incidence. That is, the angle between the line of travel of the projectile and the surface impacted. Hit something square — called “normal” in physics-speak — and it, perforce, absorbs all the impact energy. Hit it at a sharp angle, a glancing blow, and the energy absorbed is small and the projectile escapes, taking most of the energy with it. Here’s where gun choice enters the fray, folks.

When it comes to putting a hole through armor, we have to consider three different aspects of the physical object being used as the can-opening tool: speed, hardness and shape.

Faster is better, until the speed creates sufficient energy to break or deform the projectile before it has plowed through the armor. Knights of old could wear armor that would defeat arrows, which can only achieve a certain speed. Once you have armor good enough to defeat that speed, you can laugh at arrows – not with your visor open, however.

A harder projectile will penetrate armor better than a soft one will, but again, once you reach a certain speed, the hardness fails, and the armor wins — unless the armor isn’t thick enough, a secondary consideration.

Now, physics is an interesting thing. Once we go too fast, projectiles fail, until we get enough faster still. A plastic “bullet” fired at 300 fps will bounce off of a painted cardboard surface. However, boost that same plastic “bullet” up to 15,000 fps, and it will crater a metal plate. However, such velocities are beyond our ability to generate.

Finally, we come to shape. A round object will glance off a curved surface, more readily than a pointed or flat-faced projectile will. This has been observed, and accounted for by bowling pin shooters. Despite traveling at 900-plus fps, a round-nosed bullet will glance off an edge hit on a pin, where a hollowpoint or flat-pointed bullet will dig in.

As another secondary consideration, a bullet with good sectional density (long for its weight) will penetrate better than one that has a lower density, given the same weights and speeds. That’s why the U.S. Army M1-A1-A2 Abrams tanks hurl a depleted uranium “spike” at 5,500 fps to slap a hole through whatever armor that happens to be the target. Where a regular rifle bullet might be five times as long as it is wide, the Abrams M829A1 penetrator is just over thirty times as long as it is wide.

A consideration that is outside of this discussion is accuracy: You’ve got to hit the target to do any good.

So what does all this have to do with zombies? Simple: if we hold to the classic view that the only solution to the problem is a shot to the head, then we have to penetrate the skull. Failing to do so is like smacking said T-72, but not hard enough to crack the turret. At that point, life gets interesting.

Faced with the zombie apocalypse, we’re planning on head shots as our Mjolnir. But, we have to keep speed in mind.

We have to have enough velocity. Yes, a bowling ball, dropped from above, will crack a skull, but doing so requires both the bowling ball and the height.

We need speed. We also have to have a hard bullet, as a soft one will not always do the job. Emergency room reports, police reports and coroners’ reports are replete with incidents of soft bullets at low velocities failing to penetrate the skull.

You need not search very long to find reports — albeit anecdotal, in many cases — of people who had been shot, whose only wounds were the entry and exit wounds in their scalps. The bullet skidded around the skull, failing to penetrate.

And then there is shape, and here a round-nosed bullet, especially an all-lead one, is not a wise choice.

Were we to construct a three-dimensional matrix of bullet/cartridges – one axis speed, the second bullet hardness, the third shape — we’d find that there was a “cloud” near the starting point of these, of combinations that were ready to fail. The variables are within our control, to a great extent, so it is a matter of wise selection.

Let’s take a 9mm Parabellum, and assume we’re loading our own ammo. A common practice and club match load, a lead 125-grain round-nosed bullet at just over 1,000 fps, would not be a prudent choice. Yes, it has enough speed and the bullet may be hard enough, but all the variables are on, or too close to, the edge. It would be prudent to drop to 115 grains, boost to 1,200 fps, and change to a jacketed bullet.

In .45, a swaged-bullet target load would be a similar situation. We’d be better off using a jacketed bullet, 185 grains, and as fast as we can move it.

Shotguns? Hmmm. We may well find that the anti-gunners and environmentalists have actually done us a big favor here. The soft steel of steel shot is still far harder than lead, and will — or be likely to — penetrate better than lead will. Still, headshots with #4 shot are ill-advised. Tactical, hardened, or plated buckshot will do better, primarily due to velocity. Again, don’t count on soft lead spheres at “reduced recoil” speeds of 1,000 to save your bacon.

The good news is that almost all rifles would be good choices. Obviously, not all rifles chambered in handguns cartridges would be good, but real rifle cartridges are really good T-zombie-72 armor breakers.

There is one that I have some bad news for you: the ubiquitous .22LR. Don’t just take my word for it, consider the facts: soft bullet, low sectional density, soft composition, and at best moderate speed. Yes, a .22LR will poke a hole through a lot of chance objects, but we’re really marginal here, and I cannot in good conscience recommend it for zombie control.

  • http://www.facebook.com/marksiwel Mark Lewis

    A 22lr WILL do it, it just might take two shots, thats okay because I can shove 10,000 Rounds in a back pack.
    Also my 22 can be shot by children and women easily. A Plus for a Zombie Outbreak. If a 22lr, can take a pig skull , it can take a person.
    Now is it my Go TO Caliber, heck no. But its better than nothing

    • guest

      my neighbor slaughters his own livestock. uses a .22lr pistol. if it can punch thru a cow skull prettty sure my .22r Remington rifel can do a zombie in.
      lot of stories from the great depression of famers using .22lr on head shot deer.

      • Sam

        Yeah, we use a .22 lr for cows and steers and then something like a .223 for bulls due to the thicker skulls and fat. Works well and gets the job done.

    • Ty McBoss

      I agree. Shot a watermelon twice and it did the trick. Plus it's cheap and quiet. My go to caliber.

  • http://www.facebook.com/profile.php?id=681507956 David Lance Carrico

    Well, it's a good idea to have guns that are of popular calibers, so if your next door neighbors went off craving brains you can loot their house and see what they have. And hope they're not with the anti-gun movement.

  • The Worker

    Great for a chuckle and some easy physics. Good thing zombies don't exist. Still, if you want to put it through the brain, this is a great explanation of how to do so.

    Also, it would seem, that the cone of the ocular cavity would channel any round straight into the brain for a kill.

    That would make the pic from The Walking Dead show a poor choice of targeting in the circumstance I would think. I'll take my Remington 870 with buck. =)

    • saturn2462002

      "Good thing zombies don't exist." are you kidding me? Never watched congress in action have you?

      • John O

        Three days with no food or water= zombie!

  • LostLakeDave

    Fun article! Minor correction: Good Sectional Density (SD) means the bullet is heavy for its caliber, not long for its weight. SD is calculated by comparing the mass (weight) of the bullet to the square of its diameter. Though a heavier bullet will be longer (in the same bore), a shape that lengthens the bullet won't change its SD. In other words, a spitzer and a flat nose bullet of the same weight and caliber will have the same SD. Shape has nothing to do with SD; it becomes a factor in Ballistic Coefficient.

    • The author

      Thanks, Dave, and you're right. both on SD being weight-dependant, and it being a small point. It is something to keep in mind when considering all-copper bullets.

  • guest

    this guy really comparing rolled homogeneous armor to the human skull?

    • Michael

      Some people are thick headed.

  • CoolHandLoki

    What was this about? Tanks? Physics? The human skull with ribs in it? Someones going bowling? Plastic bullets?

  • mr t

    i can say that a 22 long will drop a doe so i think that it would be enough to do a zombie in not to mention that once it goes into the skull it will bounce around inside a few times turning the brain into zombie soup not the first cal. i choose but i think it would keep you from being dinner

  • Draeger

    what if we were to go from .22 lr to 22 mag or 17 hmr. certainly a big bump in speed. still low sd though

    • Crazyfox

      Yeah but just about everyone and there brother owns a .22 lr. Easy to find ammo for.

  • RealLifeNotFiction

    Did anyone see the G&A article about the real life guy in Maine who used a 22LR pistol to shoot and kill a home invader?
    Consider that fact, Patrick!

    • Michael

      That dirtbag in Massachusetts who shot up the abortion clinic used a .22. This was many years ago. It helped the liberal thugs pass the useless assault weapon ban the Romney happily signed into law.

  • ZedHead2012

    We here at Zombie Hunter Team 1A (ZHT-1A) have no comment on this article. Like a zombie, the article shuffled, staggered, and stumbled aimlessly. Vacant, and witless, groping for a point, ever out of it's reach.

    The one and only take away: BOWLING! When was the last time you had a night outing of family fun bowling? Do it this weekend!

  • Josh Johns
    • Dan

      Yes it can!

  • HOSS

    So are we in need of knowing there are zombies out there? if so lets get the ammo out and start hunting.

  • pyroty

    I have a semi auto 22 tactical rifle. Best round is cci mini mags high velocity. These easily dig straight though 3 2by4's and gets stuck in the 4th. I have also found high velocity ap 22lr rounds you know hardened steel spike in the center yeah there 20 buck for 50 but that spike will put its self through 6 2by4's and its lab tested to be able to penetrate a kevlar bullet proof vest with leathal force

  • Sings-With-Spirits

    A .22LR can indeed penetrate a skull. It is also used extensively to slaughter large livestock in just such a manner.

    HOWEVER… in slaughtering livestock, the shot is made at point-blank range and at as close to a perfect angle as can be achieved. Such a shot would not be prudent when a group of zombies is coming to eat your brains.

    Attaining skull-penetrating hits at a reasonable range with a .22 LR using off-the-shelf ammo cannot be done consistently or reliably. Consider also that most premium self-defense .22LR ammo is actually softer than your everyday stuff and is better suited for center-mass/soft tissue hits on living individuals with a functioning biology.

    Remember that zombies tend to move in groups (the scientific term would be "mob" or "congress"), so multiple shots is not advisable: a single .38 Spl round weighs less than 4-5 .22LRs and is far easier to carry and load.

    Good thing zombies don't run with werewolves… silver is really soft. :p

  • Redleg6

    I take exception to the "rifles in handgun calibers" being not good enough. Rifles increase velocity, more than handguns. Any handgun caliber amped up by expanding gases by being pushed thru a rifle barrel, would increase speed. I've killed a lot of zombies with my .357 lever action Henry — on paper targets, anyway :)

  • h87111

    If you can kill an alligator with a .22 head shot, I'm sure you can take a Zombie.

  • DrMorbius

    Hmmm… the tank turret analogy may be better than you think; like turret armor, isn't the skull much thinner on the sides and back? Since you aren't always going to be taking frontal shots, the .22LR (and my favorite choice, the .30 M1 Carbine, despite its light, RN bullet) are going to have a much better chance if the skull is indeed thinner on the back and sides…

    • Crazyfox

      +1 on the M1. RN bullets go through skulls just fine I would think.

  • Flashing Lights

    AR-15 all the way. Anybody can make a silencer so noise is no problem. And with even more 5.56 rounds in the numbers close to the .22lr

    • Hersfelder

      But, you can carry 5000 rounds of .22LR easily in a backpack….try carrying 5000 rounds of 5.56……….

  • Billy Walsh

    Great article! Long time fan of Guns and Ammo. Have you guys seen our feature on the Physics of a Head Shot yet?? http://isurvivedthezombies.com/z-t-o-d-physics-of

  • mcian

    Cool thing about .22LR… you can send 3 or more down range quickly and defeat the armor that way. Also the fact the .22LR is much quieter than other calibers… you won;t be attracting unwanted attentiom.

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