Gun Silencer: How Does A Small Metal Pipe On The Barrel Silence A Gun?

Covert operatives and spies, especially those they show in movies, are always equipped with a handful of important tools that they carry everywhere. A gun, as you might expect, is the single most important part of their ‘go-bags’, but many agents and spies, if not all, like to carry another accessory that ensures privacy. In the covert business, not making an auditory signature when you fire a weapon is important, so gun silencers are popular add-ons for certain gun users.

You have certainly seen these in plenty of movies, but now let’s look at how a gun silencer actually works.

What is a Gun Suppressor?

gun silencer rifle

Everyone already knows that there is a loud bang when a gun is fired (For more information, read Why Do Guns Make So Much Noise?), but that isn’t always desirable in certain situations.

A suppressor (also referred to as gun silencer or sound moderator) is a device that attaches to the end of the barrel of a firearm and reduces the amount of visible muzzle flash and sound produced by firing the weapon.

pistol silencer

Credit: barbulat/Fotolia

It’s important to note that it does not entirely mute the sound of the firearm; that cannot happen under regular conditions. What it does is significantly reduce the sound when a bullet is fired, and therefore you hear quite a softer sound rather than a loud bang.

How Does a Gun Suppressor Work?

A suppressor, typically cylindrical in shape, is usually a hollow metal tube made of steel, titanium or aluminum. It consists of expansion chambers, which are actually the functional part of the accessory.

To fire a bullet, you just have to pull the trigger, but a lot goes on inside the gun to make the bullet speed at your target at such a high speed. When you pull the trigger, gunpowder is ignited behind the bullet, which creates a high-pressure pulse of hot gas. This is the extreme pressure that makes the bullet fly down the barrel at such a high speed. The moment the bullet exits the barrel, the high-pressure gas pulse expands out of the muzzle, producing a loud noise.

But what if you somehow allow the gas to expand within the barrel?

This is precisely what a suppressor does. It attaches to the barrel, adding a few inches of length to the end. Its volume is also huge; roughly 30 times more voluminous than the barrel. Furthermore, it has expansion chambers, which allow the high-pressure gas to expand through the series of chambers. As a result, the gas that comes out of the end of the suppressor is considerably expanded and has a significantly lower pressure. For that reason, the sound is suppressed, so the gunshot is much softer.

james bond silencer

Gun suppressors are a common sight in spy movies

However, there is still some release of pressurized gas; therefore, the firing of a gun is not absolutely muted, even when using a suppressor. Also, note that the boom you hear when a bullet is fired is not the only audible sound associated with firing a gun. There is also the sonic boom of the bullet, which cannot be suppressed by a suppressor.

Still, a gun suppressor is an immensely helpful accessory, especially for covert field operations. Now, the next time you see 007 carrying a revolver with a rather long accessory at the end, you’ll know he’s preparing for some silent shooting!


  1. Wikipedia
  2. How Stuff Works
  3. Indiana Public Media – Moment of Science
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Ashish is a Science graduate (Bachelor of Science) from Punjabi University (India). He spends a lot of time watching movies, and an awful lot more time discussing them. He likes Harry Potter and the Avengers, and obsesses over how thoroughly Science dictates every aspect of life… in this universe, at least.

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