Defeating Metal Detectors

Metal detectors, as their name would imply, detect metal. If you need to get weapons past a metal detector and into a secure area (or if you are trying to prevent weapons from getting into your secure area) then you will need to consider weapons that are not made of metal.

Composite materials, and ceramics, will not be detected by a metal detector. Ceramic knives, scissors, scalpels and other sharp objects will slide through – your only obstacle is hiding them well enough not to be seen by the trained officer’s eye. Since ceramics are not metal, but its uses, hard- and sharpness grades are the same or better than steel, weapons made from it is just as effective and also weighs a lot less than steel. If you need to get a blade through security, go with ceramics.

Recently, the use of porcelain to make knives has been a popular thing - these will not set off a metal detector either.

Now, what you’ve got to remember is that just because the blade won’t trigger the metal detector, that doesn’t mean there’s no metal in the handle, in screws and whatnot else comes with the fancy blade.

Wooden clubs, such as a 'tire thumper' will not be detected, nor will wooden martial arts weapons such as nunchaku. Polycarbonate slingshots, such as the Scout Hunting Slingshot, firing glass marbles can cause serious injury (make head shots) at close range, but contain no metal to be detected. A slingshot modified to shoot 'bodkin darts' can even defeat soft body armor at close range.

The average metal detector doesn't detect metal in the shoes. The electromagnetic pulse does not reach down completely to floor level due to calibration and other issues.  A razor blade, for example, in the heel of your shoe may not be detected. Or, you can carry a ceramic razor blade, that isn't detectable by the metal detector, or for a better grip a ceramic razor blade escape knife.

The Undetectable Firearms Act of 1988 (18 U.S.C. § 922(p)) makes it illegal to manufacture, import, sell, ship, deliver, possess, transfer, or receive any firearm that is not as detectable by walk-through metal detection as a security exemplar containing 3.7 oz. (105 g) of steel, or any firearm with major components that do not generate an accurate image before standard airport imaging technology. Because of this law, you won't find any commercially manufactured firearms that are undetectable by a metal detector. That being said, it is not particularly difficult to build a firearm, containing almost no metal, that would fire low pressure rounds like the .22LR (but building such a gun would violate the law).

To learn more about how metal detectors work, read: Users’ Guide for Hand-Held and Walk-Through Metal Detectors NIJ Guide 600-00