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C S I Don’t Think So

GunfightEver since I was a kid, I was fascinated by the capabilities of bullets. My father was a police officer, so we had access to an outdoor shooting range anytime we wanted. We experimented endlessly. My mother freaked out endlessly when she went to look up a phone number and found that our phone books had been shredded in the name of science.

Since then, I’ve continued experimenting with the physical characteristics of bullets in real-world situations. By contrast, bullet manufacturers test bullets by using uniform standards, most commonly in long, rectangular blocks of ballistic gelatin. This is clear Jello basically, but more dense. It’s produced in blocks at a standard density so that results will be consistent and differences in bullets can be measured. Gelatin is used because it’s considered a fairly good proxy for human flesh.

In a standard test, a bullet is fired into one end of the gelatin block. Because the gelatin is almost transparent, it’s possible to see the wound channel the bullet caused, exactly how far the bullet penetrated, if it broke into pieces, and if it deformed. The bullet is dug out of the gelatin and can be microscopically examined. This data provides a baseline of results that can be used not only by bullet manufacturers, but also by doctors and medical examiners who deal with gunshot wounds.

However, it’s not much fun looking at gelatin blocks because they don’t answer many other real-world questions. Will a bullet go through a car door? Can you shoot through walls? Do bullets bounce off windshields?

Much of what we see in movies and TV regarding bullets is fantasy. Though it might seem harmless, depending on these myths in the real world could be fatal. For instance, on a popular TV adventure series, two main characters wanted to penetrate an armed perimeter and decided to do it by driving a car into the protected area. The savvy hero prepared the car by pulling off the door panels and stuffing them with phone books, claiming that this would stop the bullets.

Unless you’ve tested this idea, it sounds like it should work. Wrong!

road sign. kelso, ca. 1999.I’ve tested bullet penetration with lots of phone books. A 9mm round shot from a handgun will penetrate three thick phone books. The same round will go through quarter-inch diamond-plate aluminum which is an alloy harder than pure aluminum. The sheet metal used for car doors is maybe 1/32nd of an inch thick. Even if it’s a fat 1/16th of an inch, that’s only a quarter the thickness of the diamond plate I tested. A 9mm round fired from only a pistol would easily pass through a car door, two phone books, and then probably punch through the other side of the car.

In the TV show, the bad guys were shooting AK-47s which have far more power and bullet speed than a 9mm handgun. The hero should have looked like Swiss cheese.

Another common scenario is the shoot-out inside a home or office. Bad guys and police alike pop their heads and weapons around corners, fire, then withdraw behind the corner.

Unless the walls are brick, which is uncommon for interior walls, these people are shooting at each other with nothing more than some two-by-fours and sheetrock protecting them. A 9mm handgun bullet will easily pass through at least three or four two-by-fours and a couple of layers of sheetrock. This means that it’s not necessary to wait for someone to pop their head around a corner to get a shot at them. All one has to do is shoot right through the corner. This will work with a .38, a 9mm, or a .45 handgun. If the character has a rifle, fogeddabouddit. The walls might as well be paper.

What about windshields? This is an area of great variability. Because windshields are slanted and made of a tough combination of glass and plastic, it’s difficult to predict what will happen upon bullet impact. The result depends on the caliber of bullet, bullet shape and composition, what type of gun fired the bullet, and where the gun was fired in relation to the car. Numerous police accounts document handgun bullets ricocheting off windshields.

Head on, the slant of a windshield could very well cause a .38 caliber or 9mm slug to ricochet. Many law-enforcement officers use hollow-point bullets. However, hollow-points have less mass than a full metal jacket round and are more likely to ricochet, partly because some of the bullet’s energy is absorbed by the deformation of the hollow cavity during impact. Just as cars have crush zones to absorb impact during a crash, the hollow-point bullet has a built-in crush zone that may sometimes make it ineffective against a windshield.

The heavier .45 caliber handgun bullet has a much better chance of penetrating a windshield than a .38. Also, once one bullet has hit a windshield, even if it ricochets, it may cause tiny fractures that weaken the glass so that subsequent shots will then shatter the windshield and penetrate much more easily.

Gelatin has its place: in desserts. For me, real-world physical testing is far more valuable.

Matthew Bayan is a writer and a firearms expert. Learn more at