TLDR: Yes, but not much.

Holy Hannah, what a question. This one came from crime writer James Pierson, who tells me he’s nearing completion of his crime novel. Here’s how he laid it out:

So I have my rogue special forces guy and everyone is hunting him. He’s taken shelter in a cottage where he had to kill some guys, all of whom were wearing body armour. Anyway, the bad guys have reinforcements on the way. I mean a lot of cavalry, all armed with carbines and military-grade weapons.

My guy dons body armour. He then makes a human wall from the guys he killed earlier. Let’s say it’s two bodies high, two bodies wide. He doesn’t strip the bodies of their body armour. So the bad guys’ cavalry charge in, and they’re faced with the hero hiding behind a stack of bodies. The requisite firefight follows. Let’s say the firefight takes place over a distance of say 20 feet, so pretty close range.

So here’s the question. How much protection would dead bodies provide?

To clarify, Pierson said all of the bad guys are military characters.

The verdict depends on two primary variables. I’ll go over each separately.

Question #1: What Kind of Body Armor are the Corpses Wearing?

The first step is to figure out what kind of body armor is present on the corpses of the military members the protagonist is hiding behind.

Generally speaking, body armor is divided into two categories: ballistic resistant (for guns) and stab resistant (for edged weapons). This distinction is important, because the materials and designs in each type aren’t interchangeable. In this case, it’s a safe bet the military characters are wearing ballistic resistant armor.

Within that type are five different levels that relate to how much abuse the armor can take from a projectile:

• IIA – light handgun ammunition
• II – intermediate handgun ammunition
• IIIA – heavy handgun ammunition
• III – rifle ammunition
• IV – heavy rifle ammunition

I put general labels on the levels for quick reference. If anyone is curious about the specifics, check out this PDF and this website from the National Institute of Justice. This video does a good job of explaining it, too:

The level of armor used by a military organization can depend on the country, branch of service and mission. At the forefront is the balance between protection, weight and cost. For example, level IV armor offers exceptional protection, but it’s also bulky and expensive.

I’m going to go out on a limb and assume the military characters are using IIIA armor, suitable for protection against larger handguns like the .357 magnum and the .44 magnum. It just as easily could’ve been level III or IV, but I’m thinking the characters would favor mobility over protection. The verdict will be the same either way, as you’ll see in a minute.

With the type of armor for the wall of corpses in this scene down, it’s time to move on to the next question.

Question #2: What Kind of Firearms are the Bad Guys Using?

The next question is whether a 2×2 human wall of armored military characters would provide adequate protection in a firefight taking place at a distance of 20 feet. If the bad guys are decked out military characters, my guess is they’re using 5.56mm or 7.62mm caliber rifles (roughly equivalent to .223 and .308 calibers for those of us not on the metric system). They may also have handguns, but I’d be willing to bet they’re well-trained enough to know they need to use rifles to punch through that human wall. And it won’t take long before they do.

That’s because body armor isn’t designed to be abused over and over again. It’s adequate for a few rounds – say, a half dozen depending on the situation – before the materials and design begin to lose their ability to disperse kinetic energy from a projectile. That’s why military and law enforcement organizations replace armor after it’s been shot.

On top of that, those 5.56mm and 7.62mm rifles are going to punch through that level IIIA armor without too much trouble. Their accuracy will be compromised, but in a firefight odds are at least one shot will find its way to the main character behind the wall. The same would be true if you backed the bad guys up from 20 feet to 100 feet.

The Verdict

I’d say the protagonist hiding behind the corpse wall has about 30 seconds tops in an intense firefight before it’s time for a Plan B. Remember that body armor doesn’t typically cover every inch, either. Some bullets may slip past the armor, through flesh and exit into the protag’s position.

What About the Fact there are Several Layers of Body Armor?

The 2×2 wall certainly adds extra protection, but doubling up on body armor doesn’t work like 1 + 1 = 2.

That’s because of what’s called “back face deformation.” Body armor may stop a projectile, but some of that energy continues traveling through the front armor plate, into the person and against the inside wall of the rear plate. This creates a sort of indentation that’s called back face deformation. It’s an important part of body armor testing, because a lot of it can result in internal injuries to the person wearing the armor.

That rear plate isn’t designed to absorb projectiles coming at it from within the person’s body. In the case of the 7.62mm and 5.56mm rifles, the back face deformation is going to pound through the rear plate and keep going. The projectile may then hit the front plate of the next corpse and end its journey there. But do this over and over again, and the armor is going to fail.

Could I be wrong? Are there examples in the real world of doubling up working? There might be. But I’d bet the verdict is still the most likely outcome for this scene.

Could a Few Tweaks Fix the Corpse Wall?

To offer more flexibility in the scene, the military characters making up the corpse wall could wear level IV armor. That could buy the protag extra time. The point remains the same, though. No body armor on the planet is 100 percent bullet-proof. Even the ones that do stop a bullet won’t continue doing so for long. That’s not saying much given the lead military rifles can put in the air.

How Does Body Armor Work Anyway?

Body armor works by dispersing the energy from a projectile away from the person wearing it. It’s sort of like a soccer ball getting trapped in goal netting.

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