October's issue of American Rifleman is stocked full of insiders and insights on the firearm industry. One piece, by Jeff Zimba, focuses on suppressors (silencers for the uninitiated):
The Real Scoop On Sound Suppression
There are a lot of myths surrounding suppressors.
Here is a primer on their technical functionality
and practical applications.
Thanks to Hollywood, gun mufflers, sound suppressors
or “silencers”—one and the same—are viewed in
a negative context by many non-shooters. But the
truth is that noise suppressors are used daily—as
they have been for more than a century—to enhance
safety, ease instruction and improve accuracy for shooters of
How Do They Work?
The first thing you need to understand is that when a cartridge is fired, there is no gunpowder “explosion” in the way that some may think. Smokeless gunpowder does not explode, it just burns very fast. The primer ignites when struck by the firing pin, and the powder is ignited by the primer. As it burns, it forms a very high-pressure gas, forcing the bullet down and out the barrel followed by all the residual hot gas. The loud “boom” you hear is the expulsion of gasses happening all at once, with little or no restriction.
To put the function of a sound suppressor it in its simplest terms, the suppressor works by slowing, redirecting and cooling the hot gasses created when the cartridge is fired. We can get into all kinds of scientific terminology, but that is the general function. If we relate it to something we are all familiar with, it will be easier to understand. Think of a balloon. If you release the gas very fast by use of a pin, it will make a “boom.” If you untie the knot and let go, the high-pressure gas inside will bleed out a little slower through the sputtering neck, making much less noise. If you hold the end when untied and slowly let the air out by using pressure of your fingers to control the flow, it will make very little noise, if any. A modern suppressor would fit roughly between the last two examples.
If you were to look at an X-ray of a silencer, depending on when it was made and who made it, you would likely see a few common features. There would be an expansion chamber close to the muzzle, a series of baffles that redirect the escaping gasses and end caps holding everything together. That is where the similarities end. Early sound suppressors used “wipes” that were constructed of a soft material that projectiles would pass through, closing up quickly behind them. Another effective type of suppressor was (and still is in some cases) an artificial environmental suppressor, or “wet can.” This suppressor typically uses no wipes, but performs best when a cooling liquid is introduced to the suppressor before firing. As the gasses cool they lose “energy” and are quieter than hot gasses.
Get the full scoop on suppressors on American Rifleman online digital magazine.