Terminal Ballistics: Shooting Through Walls

Drywall, insulation, plywood—what exactly do these materials and combinations of them do to the terminal ballistics of premium defensive bullets?

As someone who owns a handgun and is willing to take action to defend you and yours, you’ve certainly given thought to the possible consequences of firing that gun within your home. There are many premium handgun bullet designs that will give fantastic performance through all sorts of media.

But what happens in the event of a missed shot in the home?

I was intrigued to see what these premium bullets would do in a few “real-world” environments, such as an interior wall with studs or an exterior wall with drywall, fiberglass insulation and plywood exterior.

• Do certain materials cause different behavior?
• Will the premium bullets whistle through a door with enough apparent energy to wound, maim or kill?
• What will it take to stop a handgun bullet?
• What effects do caliber and bullet weight have?

While my testing was the “rudimentary/backyard” style instead of some controlled laboratory environment, it’s real … and there were some informative and eye-opening results.

Gathering Guns and Ammo

Officer Mark Nazi from the Catskill, New York, police force and co-owner of Double Eagle Tactical Training and I got together with some of our favorite handguns and a variety of makes and models of premium ammunition: S&W Model 36 in .38 Special, a Glock G45 in 9mm Luger, Mark’s personal-carry gun—a Glock G22 in .40 S&W—a Kimber 1911 TLEII in .45 ACP and … just to add some spice, my own Ruger BlackHawk in .45 Colt.

Ammunition ran as light as the 110-grain bullets for the .38 Special (Hornady Critical Defense +P) to the 325-grain slugs in the .45 Colt (Choice Ammunition’s Bear load, featuring a wide, flat-nosed, hard-cast bullet). Barriers included one interior wall comprising two pieces of sheetrock screwed to a pair of 2×4 studs and an exterior wall comprising one piece of drywall, studs, fiberglass insulation and a plywood exterior.

(Now, before you start to find fault with these simple designs, please realize that we were not trying to build a home; rather, we wanted to find the effects of common building materials on premium handgun projectiles' terminal ballistics.)

We needed a way to stop our bullets—with minimal damage to the design. Mark brought along an old bulletproof vest that we attached to the back side of our mock wall, allowing it to move enough so as to not overly influence the shape of bullet. We recovered all but one projectile.

Mark and I then discussed the average distance at which a shooter would be using a handgun in the house. We settled on 10 feet and set the targets accordingly.

Bullet Trio

Let’s start with this premise: Nearly all handgun bullets, including those from a .22 Long Rifle, will penetrate a couple of panels of sheetrock … unless a stud, pipe or electrical wire is hit. While wooden studs and drywall aren’t the only combinations used for home construction, they represent very common choices.

Accordingly, different construction materials will have varying effects on any bullet (for instance, masonry construction is much tougher than the thin wood paneling that was so popular in the 1970s) regarding its deformation and retained energy. However, observing the ferocity with which our test bullets whistled through both barriers, along with how much they moved the vest (which was stapled to the top of the target so it could rotate upward), showed us both the varying power levels of the cartridge/bullet combinations, as well as which bullets expanded regularly and which plugged up with material.

S&W .38 Special

I tried a trio of bullets in my snubnose S&W .38 Special: the 110-grain Hornady FTX Critical Duty, 130-grain Winchester PDX-1 Defender and the 158-grain Hornady XTP in my handload. Firstly, of all the cartridges tested, the .38 Special had the least visible movement of the vest. Secondly, all three bullets were nearly plugged with gypsum from the drywall.

More Ballistics Information:

Expansion was rather uniform, with expanded bullets measuring between .429 and .486 inch (from the original .357-inch diameter) and weighing just under or a bit over original weight (the drywall material added to the bullet weight). I don’t doubt the effectiveness of the .38 Special cartridge—especially in the +P guise—and although the 2-inch barrel of the Model 36 gives up a bit of velocity, in a crowded house, this cartridge came out as my favorite.

9mm Luger

The 9mm Luger offered a visible increase in momentum, pushing the 135-grain Hornady FTX bullet at slightly more than 1,000 fps from the 4-inch barrel (the 110-grain .38 Special load lists an equal velocity—but with a 4-inch barrel, not the 2-inch barrel of the Model 36), and it expanded to an average of 0.576 inch, retaining 131.8 grains of its original 135. This might have been an instance of velocity gain due to barrel length, but the visual impact of the 9mm into the vest had a definitive advantage over the .38 Special.

.40 S&W

Bumping up to the .40 S&W, things changed radically. The interior wall offered virtually zero resistance, other than to start the expansion, but the exterior wall didn’t offer much more, because our bullet-stopper vest was flipping around. Mark carries the Federal Hydra-Shok 180-grain load on duty, and that load is well-proven throughout the law enforcement community, as well as the CCW crowd.

I could say the same about the 155-grain Federal HST load; that HST has been my favorite defensive bullet for quite some time. The 180-grain Hydra-Shok expanded from .400 to .717 inch, weighing 183.6 grains (picking up material through the wall). The lighter HST load expanded to .635 inch, weighing 158.2 grains. The .40 S&W has bridged the gap between the 9mm and .45 ACP for some time now and gives a great blend of low recoil and wonderful terminal ballistics.

.45 ACP

Turning to the classic .45 ACP, its additional throw weight more than made up for the diminished velocity, especially at the test distance we chose. The .45 ACP is my favorite all-around defensive cartridge.

There are also some wonderful projectiles available for the .45 ACP; and among those tested, there were a few that gave excellent performance. Regarding momentum: The visible movement of both the wall and the bulletproof vest was the greatest we’d seen as of that point, with most designs being nearly equal (from a visual standpoint).

As they showed me during a more formal test at the Federal plant in Anoka, Minnesota, both the Hydra-Shok Deep and HST gave stellar performances. Browning’s BXP load and the Sig Sauer V-Crown load (the latter being a bullet from Sierra) also had high weight retention and good expansion throughout the test.

.45 Colt (just because)

When firing the Choice Ammunition Bear load, the .45 Colt in my Ruger Blackhawk—replete with a 7½-inch barrel—showed an amazing amount of energy. It blew the vest 3 yards off the two combined walls, giving far and away the most dramatic impact. That 325-grain, wide, flat-nosed, hard-cast bullet retained 95 percent of its original weight, expanding to .548 inch in diameter and hitting our mock walls like a category 5 hurricane.

What Does It All Mean?

Well, Mark and I clearly established that neither the interior nor the exterior wall stopped much. Even the combination of the two didn’t offer much resistance. In fact, we added three more sheets of ½-inch plywood to the mix and, with the exception of the .38 Special, our premium bullets still escaped the obstacle we’d created. I can say rather confidently that firing through the exterior wall of the average house does little the terminal ballistic potential of a round and could very easily result in the death of someone standing on the other side.

As basic as it was, this little experiment opened my eyes to just how careful one has to be when even considering using a firearm in the home. I want to know exactly where beds, couches, desks and seats—as well as any other possible location of a person in my home—are, and I want to be able to establish that from many different angles from within my home.

Premium bullets are exactly that: They give the best performance available. Of the bullets tested, it seemed the Hornady FTX design had the greatest tendency to plug with wall material and have its expanded diameter reduced—at least in comparison to the figures and conformation demonstrated by shooting these bullets into gelatin.

That said, I don’t think this casts any sort of a shadow on Hornady’s design, because the parameters of bullet design can’t possibly account for the post-penetration performance through all types of barriers. As is true for any soft-point bullet delivered from any firearm, the higher the impact velocity, the greater and more radical the expansion. With that expansion comes a decrease in velocity … and that might very well equate to a saved life on the other side of that wall.

I have a favorite handgun bullet, and I make no excuses about being such a fan: Federal’s HST is one of the best designs I’ve come across. Yes, the Hydra-Shok Deep solved many of the issues associated with the original Hydra-Shok design. However, the recovered shape, weight retention and wound channel of the HST, combined with the accuracy of Federal’s loaded ammunition, has earned that bullet a position at the top of my list.

There was nothing highly technical about this test—with the possible exception of the vest to stop the bullets. However, if you had to replicate it with wet newspapers, I’m sure it would work. Should you find yourself curious about the combination of handgun/cartridge/bullet you’ve chosen, you can easily replicate this simple experiment using sample materials of those used in your home.

It’ll make you a more careful—and more confident—shooter.

Editor's Note: This article originally appeared in the April 2020 issue of Gun Digest the Magazine.

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