Why Airport Metal Detectors Won’t Pick Up Bullets

Yesterday, we wrote about how they found a single bullet found on the floor of an Alaskan Airline. We noted, “You
d think that
d be something the metal detector would pick up.”

Michael wrote in to say, no, you could wear a full lingerie set made from .22 caliber bullets, but…

    “Metal detectors won’t pick it up. They work by inducing a magnetic field in ferrous metals, and then sensing the resulting field.

    Cartridges (bullets) are composed of: copper, lead, brass, smokeless gunpowder (nitrocellulose/nitroglycerin), and a primer which does have some ferrous metal in it, but its so minimal I seriously doubt anything would pick it up. The primers [weighs] only a few grams, and only about 1/2 of its mass is metal.

    …That and something like a 747 is designed to fly (and remain pressurized) with something like 5 or 6 windows completely removed… A single (hell, an entire magazine) shot won’t cause the aircraft to depressurize.”

Thanks, Michael, that is some good chunky info. However, our concern wasn’t about someone shooting the windows and depressurizing the airplane. Rather, we were concerned about the bullets being used to depressurize people’s skulls, as in the Pro Diablo Ultimate Hunting Slingshot?

UPDATE: Nick writes,

    “That email about metal detectors only detecting ferrous materials is a load of bunkum – metal detectors work by inducing a current in any conductive metal (eg, any metal) – it doesn’t have to be ferrous to be detected. See [here at howstuffworks for] details.

    The real reason it wouldn’t detect a bullet is that even in most paranoid airports, the threshold is set too high for a single bullet to set it off. If your [measly] wristwatch with a metal band doesn’t do it, nor will one measly bullet.”