If you shoot a bomb, will it explode?

Answers to your questions about the news.
Dec. 8 2005 6:29 PM

If You Shoot a Bomb, Will It Explode?

What happens when a bullet hits dynamite.

Download the MP3 audio version of this story hereThe Explainer now has its own free daily podcast; click here to learn more.

A potentially explosive situation?
Click image to expand.
A potentially explosive situation?

On Wednesday, air marshals in Miami shot and killed a man who was pretending to carry a bomb off a plane. According to an official account, the marshals ordered the man to get on the ground and then opened fire when he reached into his backpack. A government spokesman says the marshals acted properly and that "this was a textbook scenario." If he really had been toting a bomb, could bullets have set it off?

Daniel Engber Daniel Engber

Daniel Engber is a columnist for Slate

It depends on the explosive. Some bomb materials are highly sensitive to impact; if you shoot a gun at a stick of dynamite, for example, there's a good chance you'll set it off. Others are less susceptible to gunfire. The military tries to make its explosives as durable as it can, since you don't want soldiers blowing up from the impact of a single bullet. A block of C4 plastic explosive can withstand a rifle shot without exploding. You can even set one on fire without too much worry.

Advertisement

That doesn't mean a bomb made from C4 (or another insensitive explosive like TNT) is impervious to gunshots. Such a bomb would have a detonator, which is far more vulnerable. The detonator serves as a mini-bomb that produces enough energy to blow up the main explosive. Here's how it works: A power source—usually a few batteries—provides an electrical charge that sets off a tiny explosion in one part of the detonator. This sets off another, somewhat bigger charge, which in turn ignites the payload of C4 or TNT. If a bullet were to strike the detonator, it could easily set off the more-volatile explosives stored inside.

You'd have to be an unbelievable shot to pull that off, though. In general, detonators are very thin—about the diameter of a pencil—and only a few inches long. If the man in Miami had been carrying a bomb, the chances of an air marshal accidentally shooting the detonator would be very small. If the bullet had hit the TNT, it might have passed right through. It's also possible that a stray bullet could disable the bomb. A bullet that happened to strike the batteries could jar them loose and cut off power to the detonator.

Although some terrorists use stolen, military-grade explosives, many rely on improvised bombs that tend to be far more sensitive. The shoe-bomber Richard Reid was trying to blow himself up with a very unstable mixture called triacetone triperoxide, which is brewed from acetone, hydrogen peroxide, and a strong acid. He had trouble lighting the fuse; a gunshot might have done the trick.

As for the man in Miami, we don't even know if the air marshals shot at him with conventional bullets. In the past, marshals have used special ammunition designed for airplane safety. One variety consists of little pouches of Kevlar filled with lead shot. While these could disable (and perhaps kill) a person, the distributed impact they produce would be less likely than a conventional bullet to blow up a bag of explosives. Bomb technicians shoot special types of ammunition at suspicious packages all the time: A slug from a water cannon or a burst of powder from a 12-gauge shotgun can smack the bomb in such a way that it breaks apart without going off.

Got a question about today's news? Ask the Explainer.

Explainer thanks Jack McGeorge of the Public Safety Group, Chris Ronay of the Institute of Makers of Explosives, and reader Drew Vance for asking the question.

TODAY IN SLATE

History

Slate Plus Early Read: The Self-Made Man

The story of America’s most pliable, pernicious, irrepressible myth.

Rehtaeh Parsons Was the Most Famous Victim in Canada. Now, Journalists Can’t Even Say Her Name.

Mitt Romney May Be Weighing a 2016 Run. That Would Be a Big Mistake.

Amazing Photos From Hong Kong’s Umbrella Revolution

Transparent Is the Fall’s Only Great New Show

The XX Factor

Rehtaeh Parsons Was the Most Famous Victim in Canada

Now, journalists can't even say her name.

Doublex

Lena Dunham, the Book

More shtick than honesty in Not That Kind of Girl.

What a Juicy New Book About Diane Sawyer and Katie Couric Fails to Tell Us About the TV News Business

Does Your Child Have Sluggish Cognitive Tempo? Or Is That Just a Disorder Made Up to Scare You?

  News & Politics
History
Sept. 29 2014 11:45 PM The Self-Made Man The story of America’s most pliable, pernicious, irrepressible myth.
  Business
Moneybox
Sept. 29 2014 7:01 PM We May Never Know If Larry Ellison Flew a Fighter Jet Under the Golden Gate Bridge
  Life
Dear Prudence
Sept. 29 2014 3:10 PM The Lonely Teetotaler Prudie counsels a letter writer who doesn’t drink alcohol—and is constantly harassed by others for it.
  Double X
Doublex
Sept. 29 2014 11:43 PM Lena Dunham, the Book More shtick than honesty in Not That Kind of Girl.
  Slate Plus
Slate Fare
Sept. 29 2014 8:45 AM Slate Isn’t Too Liberal, but … What readers said about the magazine’s bias and balance.
  Arts
Brow Beat
Sept. 29 2014 9:06 PM Paul Thomas Anderson’s Inherent Vice Looks Like a Comic Masterpiece
  Technology
Future Tense
Sept. 29 2014 11:56 PM Innovation Starvation, the Next Generation Humankind has lots of great ideas for the future. We need people to carry them out.
  Health & Science
Medical Examiner
Sept. 29 2014 11:32 PM The Daydream Disorder Is sluggish cognitive tempo a disease or disease mongering?
  Sports
Sports Nut
Sept. 28 2014 8:30 PM NFL Players Die Young. Or Maybe They Live Long Lives. Why it’s so hard to pin down the effects of football on players’ lives.