Is an AR-15 Appropriate for Home Defense? Part One: Penetration Issues


Is an AR-15 appropriate for home defense? That’s a really big question, isn’t it? Way too big a question for a single article to address in adequate detail. So we’ll look at one issue at a time.

First, since AR-15 rifles cause all nature of mainstream media histrionics, we’ll consider the “high-power” issue, which in a practical sense, translates to penetration. If you torch off a .223 Remington or 5.56mm round indoors, will the building explode? Listening to the news, you might think so.

More rational, and less pants-wetting thoughtful consideration yields a different conclusion when we look at penetration specifically. If you shoot an AR-15 inside your home or apartment, and miss your target, will the projectile continue to pass through interior walls, exterior walls, cars, dump trucks, and eventually the nearest ocean before embedding itself deep under the sea floor?

These are curious questions. Being curious, I decided to build some very small walls and shoot them with an AR-15. I shall call them mini-walls.

I shall call them.... mini-walls. I built four in total, each with sheet rock on both sides.
I shall call them…mini-walls. I built four in total, each with drywall on both sides.

When considering home defense options, from strictly a penetration point of view, the basic question is: what will over-penetrate through walls, furniture, and your shiny new Ninja Blender? A heavier and slower pistol round, or a very light and fast rifle round?

The thing about light and fast bullets is that they tend to get upset–specifically, fragment or tumble—when they hit harder things like walls or furniture. Tumbling and fragmenting both result in a very rapid loss of velocity and energy, therefore a lightweight rifle projectile going somewhere around 3,000 feet per second may actually have less unwanted penetration than a pistol round traveling in the 1,000 feet per second range.

Before sharing results, I should present a couple of disclaimers.

  • I suck at construction, so if you are a professional carpenter, just hold your lunch down while looking at the photos of my mini-wall construction efforts. I’m only shooting them to pieces, not putting them in my house.
  • I didn’t paint the walls. This may sound trivial, but several coats of dried paint are hard, and likely to make some difference in the rate that lightweight, high-velocity bullets break apart.
  • The walls are close together. As you’ll see, some of the projectiles started fragmenting pretty quickly. If they had more time to spread out before hitting the next wall, I suspect they would have lost a lot of energy. Think of a shotgun pattern. When the pellets are still “clumped” together at short range, there’s more penetration than when they spread out to a three foot pattern a little further out.
  • I’m not a ballistic scientist. I just got curious, decided to do some basic testing, and share what I found. Do with the findings what you will.

With all that said, I looked at two different “interior wall” simulations. In one scenario, I used drywall (Sheetrock) only. I assumed the projectiles only hit drywall material of multiple walls. For the other scenario, I added a piece of 3/8-inch particle board between walls one and two—just to simulate junk inside walls like cross beams, furniture, or any number of other things besides wallboard that may be inside a home. All shooting was done from “indoor” ranges of five yards.

The first step was to establish some pistol round baselines. I shot both 9mm full metal jacket and 9mm Hornady Critical Duty 135-grain hollow point rounds through the walls—both with and without a wood barrier in the mix. I also shot a “standard” practice ammo full metal jacket .223 Remington round, in this case an American Eagle 55-grain projectile.

AR-15 Drywall penetration 4
Shooting through drywall only, the 9mm projectiles went right through all four walls and right out the back. So did the .223 Remington full metal jacket loads.

While both the 9mm and .223 Remington projectiles went through all four walls (eight pieces of Sheetrock), the .223 started to upset after passing through the second wall in the drywall-only test. As you can see in the photos, it went through walls three through four bumbling and tumbling—and losing lots of energy in the process. But the path stayed true, and the .223 projectiles were not knocked off-course.

The 9mm rounds? They didn’t deviate a bit and went through all four walls like butter. If I had four more walls, I suspect the pistol rounds would have gone through those too.

The .223 projectile started to tumble, as expected, after passing through just one wall.
The .223 practice ammo projectile started to tumble, as expected, after passing through two walls.

When I added a piece of 3/8-inch particle board to the mix, the .223 full metal jacket round started to tumble right away. And it never did exit the fourth wall. Again, the 9mm bullets went through all eight pieces of Sheetrock (four walls) and the particle board without upset or deviation.

Premium ammunition

With some semblance of a baseline, I wanted to try several .223 hunting and self-defense loads to see how they would react to interior walls and wood obstacles. This was not intended to be a test of specific ammunition performance, as each variety is designed for different purposes, but rather an observation of what would happen when various projectiles encountered interior walls.

Some of the loads tested against interior walls
Some of the loads tested against interior walls.

Of the five loads tested in this scenario, only the DoubleTap Ammunition 55-grain Nosler Ballistic Tip and Hornady 55-grain V-Max are designed to somewhat expand when they hit something. The Speer Gold Dot, Black Hills Barnes TSX, and Winchester Ranger loads are built to penetrate deeply and expand in a controlled fashion, so I expected those to go through interior walls without too much upset. Again, this was a curiosity exercise, not a performance test of one ammunition type against another.

You can see that the Barnes Ballistic Tip and Hornady V-Max projectiles started to break part, as designed, quickly.
You can see that the Barnes Ballistic Tip and Hornady V-Max projectiles started to break part, as designed, quickly.

As expected, the Nosler Ballistic Tip and Hornady V-Max projectiles started to break apart after passing through the first wall. The other three, again as expected, displayed more controlled expansion throughout. The Speer Gold Dot did start to tumble between the second and third wall.

All five loads passed through all four walls.
All five loads passed through all four walls. The Hornady V-Max and Nosler are top left and right, respectively.

So, using only drywall segments with no wood barriers, all five loads passed through four mini-walls. As you can see, the exit patterns of the Nosler and Hornady fragmenting projectiles show that those were heavily fragmented by the time they left—most likely having lost much of their initial energy.

As the DoubleTap Ammunition 55-grain Nosler Ballistic Tip and Hornady 55-grain V-Max displayed the least unwanted-drywall penetration, I wanted to re-introduce the 3/8-inch particle board barrier. Remember that the basic idea behind the wood barrier is to account for material inside walls or furniture in front of, or behind, walls.

Both loads displayed aggressive fragmentation.
Both loads displayed aggressive fragmentation.

Both loads started to fragment quickly. After passing through one wall and the wood barrier, the holes in wall number two started to resemble a shotgun pattern. By the time they exited the additional walls, it was clear that all that was left of the additional projectile was fragments.

Pieces and parts made it to the fourth wall.
Pieces and parts made it to the fourth wall.

So what does all this mean?

Again, we’re dealing with somewhat uncontrolled observation, but a few things stood out.

  • The pistol rounds were seemingly unaffected by the drywall and/or wood barriers. There was no observable deviation or fragmentation of the 9mm projectiles. You’d be safe counting on a pistol round to keep going, and going, and going. After all, premium pistol ammunition is designed to expand, and lose energy, when striking liquid-based targets—not walls.
  • The full metal jacket .223 rounds tended to tumble rather than break apart when they encountered barriers.
  • The projectiles designed for rapid fragmentation (Nosler Ballistic Tip and Hornady V-Max) did in fact do that. I wish I had gel blocks to see exactly how much energy remained. By observation of the fragmentation patterns, they were clearly losing velocity and energy. How much damage would they have done to a person at that point? I can’t say more than “less” than the pistol rounds, which were still humming right along.
  • Even though the .223 rounds start with a lot more energy, they tend to lose it quickly when encountering the barriers in this test.
  • You always have to worry about what’s behind your target. Nearly all of the rounds tested went through at least four walls, although some obviously came out the back end with a lot less energy than others.
  • If you live in an apartment, you may want to assume that only softer, interior walls stand between you and neighbors. In a free-standing house, I’m confident none of the AR-15 rounds would have made it through interior and exterior walls. Windows, of course, would alter that assumption.
The Hornady V-Max (top) and DoubleTap Nosler Ballistic Tip (bottom) are excellent home defense options if you're worried about over-penetration.
The Hornady V-Max (top) and DoubleTap Nosler Ballistic Tip (bottom) are good home defense options if you’re worried about over-penetration.

Before all this tinkering, I expected that some of the AR-15 rounds would blow up early and not penetrate multiple walls. Given that almost all did, that was a bit of a surprise.

Moral of the story? Don’t trust the mainstream media. Those high-powered, so called “assault weapons” may be safer than your average pistol for inside-the-home defense.

In upcoming articles we’ll look at issues beyond penetration that weigh into the decision of whether an AR-15 is appropriate for home defense.

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