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.

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.

This is the construction, in my yard.

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 set-up.

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.

First, a 9mm 115 gr. JHP.

Went through all 4 walls like butter.

This is the exit from the 4th wall.

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.