The Box O’ Truth #12 – Insulated Walls

Since we started this project, many people have asked, “Why don’t you fill the walls with insulation before you shoot them? Maybe it would make a difference.”

Well, the standard answer is, “Interior walls, at least here in Texas, are not insulated. Only exterior walls are insulated.”

But…..who knows? Maybe it would make a difference.

The question was also asked, “Would it make a difference if the walls were spaced out more, like in a home?”

Good question.

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We had shot through two walls spaced 10 to 12 feet apart in one experiment, and saw no evidence of lack of penetration by the rounds shot.

But, being interested in giving any reasonable question a serious answer, we built 4 walls and put insulation in them.

The insulation is called “Certainteed R-13 insulation”, and is a paper-backed fiberglass type.

It is typical in this part of the country.

This is the construction, in my yard.

This is the construction, in my yard.

We placed the walls about 10 feet apart to simulate “across-the-room” distances.

We will shoot through them with some common rounds to see what happens

This is the set-up.

This is the set-up.

First, a 9mm 115 gr. JHP.

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Went through all 4 walls like butter.

Then a .40 S&W, 135 gr. JHP, because several folks have asked me to try a .40.

It went through just like the 9mm.

This is the exit from the 4th wall.

This is the exit from the 4th wall.

Then a .45 ACP, 200 gr. JHP.

Straight through all 4 walls.

I’m beginning to see a pattern here.

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How about a rifle?

Here's Tman with an AR15 shooting XM-193 Ball.

Here’s Tman with an AR15 shooting XM-193 Ball.

But we began to have a problem.

The 5.56 deviated from the straight path so much, that it only hit 2 walls and then missed the third one.

The tumbling is clearly evident.

This is the exit from the second wall.

This is the exit from the second wall.

But look where it hit the third wall.

It just barely hit the edge of the wall.

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We decided to try several more shots with the 5.56.

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It was kind of hard to line up the 4 walls and try to get the round to hit all 4 of them.

This entrance to the second wall illustrates why this was a problem.

You can see the tumbling of the round.

This caused a lot of deviation from the original path.

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Might as well try the “Street Howitzer”.

12 gauge with Remington “Slugger” Slugs.

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This is the entrance of the second wall.

This is the entrance of the second wall.

Interestingly, this is the entrance of the slug into the third wall. Looks like it might have been traveling sideways at that time. Needless to say, it exited all 4 walls

Interestingly, this is the entrance of the slug into the third wall. Looks like it might have been traveling sideways at that time. Needless to say, it exited all 4 walls.

We tried several more rounds of M-193 from the AR.

A couple more interesting pics.

This is a round of 5.56 as it enters the third wall.

This is a round of 5.56 as it enters the third wall.

Here's the back side of wall #3 where the 5.56 was headed. It was stopped by the back board of the third wall. You can see the "bulge" caused by the round.

Here’s the back side of wall #3 where the 5.56 was headed. It was stopped by the back board of the third wall. You can see the “bulge” caused by the round.

This is the dug out round. Looked like a tube of toothpaste with all the toothpaste squeezed out.

This is the dug out round. Looked like a tube of toothpaste with all the toothpaste squeezed out.

Here's the pieces of the only other M-193 5.56 round to hit the third wall.

Here’s the pieces of the only other M-193 5.56 round to hit the third wall.

Lessons learned:
  1. Insulation in walls seems to make very little, if any, difference in penetration of the rounds tested. I believe that we can put that one to rest.
  2. Common pistol rounds easily penetrated all 4 walls spaced out at room distances. This is a critical issue. Think about the inside of your house and imagine if you shot through 4 walls. Could you hit a loved one? Know your target and what is behind it.
  3. The 12 gauge shotgun went through 4 walls like they were not there. Remember this if you have loved ones in your house with you and plan to use slugs for defense loads.
  4. The 5.56 rounds deviated greatly from the original flight path once they started tumbling. This occurred after the second wall. We need to do some more tests, but need to build bigger walls so that we can make sure we capture the flight path of the rounds.
  5. Spreading the walls out at room distances seemed to make little difference for the pistol rounds, but made a big difference for the 5.56 rounds. Possibly this was due to the tumbling of the rounds causing them to deviate from a straight line.
    But this raises an important point. When you shoot a 5.56 into walls, you cannot be sure where the flight path of the bullet will go. This is an important consideration if others are in your home.
  6. It was 70 degrees, the sun was shining, it was fun shooting stuff, and this was better than the best day I ever spent at work.

4 Comments on The Box O’ Truth #12 – Insulated Walls

  1. Excellent testing as always. Presumably not all 5.56 rounds will perform as noted, particularly those designed for home defense or hunting (read expanding).

  2. I would like to see a test on the exterior wall of my new home. 3/4″ plywood to 4 inches of closed cell spray foam and 5/8″ sound deadening sheet rock on interior wall. I suspect most bullets would penetrate without issue, however I’m curious if the closed cell spray foam would help slow down the round.

  3. Did similar test a couple decades ago. 4’x8′ walls, 1/2″ drywall nailed both sides of 2×4 stud, walls spaced 10′ apart. SECOND wall had 1/4″ paneling (actual measure 3/16″ thick, same as 2×4 stud is only 3-1/2″) nailed over drywall on BOTH sides. THIRD Wall had 18ga sheetmetal nailed over the 1/2″ drywall (idea was to simulate a/c ducts which today are FlexDuct tubes instead of fabricated sheetmetal with rigid insulation- still see in commercial construction). Regardless, last wall had 18ga sheetmetal on BOTH side over drywall.

    WHAT WAS USED AGAINST THESE WALLS? < purpose was self defense with handguns, inside home or building, determine PENETRATION of bullets (i.e. if shooter MISSED the BG) how far bullet might travel). Not concerned with bullet performance other than as noted below. Caliber of ammo fired was most of the common bullets might be shot from CCW handgun

    CALIBER FIRED: Every ‘common’ handgun caliber starting with 22lr (40gr Win. solid and jhp= same) + 22mag + 32acp (only JHP) + 380acp (90gr ball and JHP) + 9mm (ball and 115JHP), 357mag (125JHP – 158gr JHP) + 44mag (180gr JHP Sierra – 240gr Hornady JHP ) + 45acp (Win. factory Silvertip 185gr JHP – SuperVel 190gr. which over PACT chrono did ~1,050fps from 3-1/2″ Detonics – Hornady XTP 185gr JHP handload . Also fired Glaser Safety Slugs in 9mm, 45acp, 44mag as well as trying MagSafe in 45acp and 44mag. Wasted a couple of 454Casull, through 4-3/4″ revolver only and didn’t use 7-1/2″ scoped brother Didn’t get around to either rifle or shotguns as paying jobs interfered with time.

    END RESULTS were not much different than what you reported.
    The 22lr went through W#1 and stopped in second layer paneling W#2.
    22mag through all walls, flying sideways as it left W#3.
    ALL OTHER HANDGUN CALIBERS, BEGINNING WITH 32acp UP THROUGH WASTE OF HORSEPOWER IN 454Casull, PASSED THROUGH ALL THREE WALLS WITH LITTLE SIGN OF SLOWING DOWN. Ball and JHP changed only the size of holes in W#3 showing BIG calibers with JHP ‘start’ to expand and create larger holes instead of normal JHP cavity ‘plugging up’ with drywall and continuing to penetrate like ball bullets.
    CONCLUSIONS: don’t need a cannon for self defense inside a home. IF SHOOTER HAS FAMILY OR FOLKS WHO’S WELL BEING THEY ARE CONCERNED ABOUT HAD BETTER USE LARGEST CALIBER THEY CAN CONTROL AND SHOOT ‘accurately’. No Bad Guy is ever stopped by a MISS. IF YOU MISS, bullets can and will travel through EVERY ROOM INSIDE YOUR HOME with enough steam left to seriously harm or kill an innocent. Even Worse, FRAME construction home that bullet could travel into your neighbors home. CEMENT BLOCK will stop ‘normal’ rounds but that glass window or sliding door does little except change ‘path’ the bullet is traveling. SHOOTER ‘owns’ that bullet once it has been fired, including consequences for damages down range.

    NOT ALL the details for ALL the bullets, enough to tell the story of be careful you hit your target when you8 pull the trigger on your favorite home weapon.

  4. FYI, forgot to add Glaser Safety slugs, did not survive the first wall and at worst with heavy caliber was mark surface first layer paneling on W#2 with NO penetration. Glaser Safety Slugs were ONLY round which had little or no lethal threat after hitting the FIRST LAYER of drywall. MagSafe uses heavier shot in some type of epoxy binder, having greater penetration than Glaser Safety. Still better than ANY other type of ammo insofar as reducing threat from penetration or glancing off a surface to go places shooter did not intend. BOTH ARE DEADLY FOR HITTING SOFT SURFACES (i.e. BG)

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