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.