How Does a Silencer Work?

By: Desiree Bowie  | 
A gun silencer quiets pressurized gas behind the bullet.
Silencer/­Getty Images


If you've watched any movie about an assassin, like "John Wick" or "Sicario," you've likely seen a character twist a thick suppressor onto the barrel of a pistol before approaching an unwitting target and firing on them. Following the pull of the trigger, there's usually a barely perceptible, ultra-unrealistic "pew pew" sound that lets you know that they've shot the gun.


In real life, a gun suppressor is nowhere near as quiet and unassuming as its big-screen counterparts, but it does reduce the loud noise associated with firing a firearm. This beckons the questions: How does a silencer work?

Let's take a closer look at the origins of this muzzle device, how it actually works and the laws surrounding it.


What Is a Silencer?

A gun silencer, or suppressor, is an attachment for firearms that reduces the noise produced when a gun is fired. It is designed to muffle the sound of the gunshot, making it quieter compared to an unsuppressed firearm.

Gun silencers have various applications, including law enforcement, military use and recreational shooting. They are valued for their ability to improve communication, lessen auditory fatigue and reduce noise disturbances in surrounding areas.



The firearm suppressor is composed of several essential parts. The outer tube or body encases the inner components, typically made of materials like steel, aluminum or titanium.

Inside the silencer, you'll find baffles that slow and redirect the high-speed gases produced when a firearm is fired. Expansion chambers further reduce gas pressure and speed. The blast baffle, situated closest to the muzzle, absorbs the initial force of escaping gases and directs them into the first expansion chamber.

Most gun suppressors have a threaded mount or quick-attach system to secure them to the firearm's muzzle. Some designs also use spacers or springs between baffles to maintain alignment. Finally, the end cap seals the suppressor and prevents gas escape.

These components vary slightly depending on the specific silencer model and manufacturer.


Who Invented the Silencer?

The invention of the firearm silencer is credited to Hiram Percy Maxim, an American inventor. In 1909, Maxim received the first patent for his innovative device, initially called the "Maxim Silencer." His motivation was to reduce the deafening noise and recoil associated with firearms.

Maxim's design featured a series of expansion chambers that effectively slowed down and cooled the high-pressure gases escaping the barrel, significantly muffling the gunshot report. This early invention was intended to preserve the hearing of shooters and minimize noise pollution, and it would become the first commercially successful silencer.


Over time, Maxim's concept evolved into the modern firearm suppressors we know today, serving various purposes in both military and civilian applications while facing legal regulations and restrictions in many countries.

How Does a Silencer Work?

Before we explore how a silencer works, it's helpful to understand what happens when you shoot a gun without any kinds of sound suppressors.

When an unsuppressed gun is discharged, the explosion of gunpowder in the cartridge generates high-pressure, high-temperature gases that rapidly exit the gun barrel behind the bullet. These gases exit the barrel at supersonic speeds, creating a loud sonic boom, similar to a thunderclap, which is commonly referred to as a muzzle blast.


Now let's look at what happens when you fire a suppressed gun. When you pull the trigger, and the bullet exits through the opening in the silencer, high-pressure gases trailing the bullet enter the suppressor.

Within the suppressor, you'll find expansion chambers, baffles and ports designed to help expand and cool these high-pressure gases. This controlled process effectively reduces the speed of the gases as they exit the suppressor.

The suppressor plays a crucial role in suppressing the supersonic crack or sonic boom generated by the bullet as it travels faster than the speed of sound. The suppressor's internal components disrupt the shockwave produced by the bullet's high-speed flight, contributing significantly to the reduction in noise associated with the gunshot.

Although the shot remains quieter with a suppressor, it's still pretty loud. The suppressor also helps reduce the visible muzzle flash, making it less conspicuous, particularly in low-light or nighttime shooting situations.

And finally, the use of a suppressor results in less recoil and muzzle rise compared to firing the same firearm without one. This improved control and reduced recoil enhance overall accuracy, especially during rapid-fire shooting.


Subsonic Ammunition

A bullet that travels at supersonic speeds cannot be silenced because the bullet creates its own little sonic boom as it travels. Many high-powered loads travel at supersonic speeds. The silencer can remove the "uncorking" sound, but not the sound of the bullet's flight.

Enter subsonic ammunition. This specialized type of firearm cartridge is designed to propel bullets at velocities below the speed of sound, typically less than about 1,125 feet per second (343 meters per second) at sea level.


This deliberate reduction in bullet velocity results in significantly quieter shots compared to supersonic ammunition. Subsonic rounds are often used in firearms equipped with suppressors to further minimize noise.

When paired with a muzzle brake, they offer reduced sound and enhanced shooter control and comfort. Like a suppressor, a muzzle brake is a device that attaches to the muzzle (the end) of a firearm barrel. Its primary purpose is to reduce recoil and control muzzle rise by redirecting and dispersing the escaping gases produced when a bullet is fired.

This redirection of gases helps counteract the forces generated during firing, making it easier for the shooter to maintain accuracy and stay on target. While a muzzle brake doesn't silence the shot like a suppressor, it significantly improves shooter comfort and control, especially when using powerful or high-recoil firearms.

But not all firearms are designed to accommodate both a muzzle brake and a suppressor simultaneously. The firearm's barrel and threading must be compatible with both devices. Some firearms may have specific adapters or configurations to allow for the attachment of both, while others may not.


Types of Firearm Suppressors

Firearm suppressors come in several types, each designed to cater to different firearms and specific shooting needs.

  1. Screw-on or thread-mounted suppressors: These are the most common suppressors and are designed to screw onto the threaded barrel of a compatible firearm. They are versatile and can be easily swapped between different guns with threaded barrels, making them popular among shooters.
  2. Integral suppressors: Integral suppressors are built directly into the firearm's barrel. This design reduces overall firearm length and creates a more streamlined appearance. They are often found on specialized firearms designed for quiet operation, such as integrally suppressed rifles.
  3. Rimfire suppressors: Designed for smaller caliber weapons like .22LR, rimfire suppressors are optimized for the lower pressures and velocities of rimfire ammunition. They effectively reduce the noise produced by these firearms, making them popular for plinking and small game hunting.
  4. Centerfire suppressors: These are designed for larger caliber firearms, including handguns and rifles. Centerfire suppressors can accommodate a wide range of ammunition types and calibers, offering noise reduction and recoil mitigation for more powerful firearms.
  5. Shotgun suppressors: Shotgun suppressors are tailored for shotguns and address the unique challenges presented by shotgun ammunition. They help reduce the deafening report of shotguns, which is particularly useful for hunters and competitive shooters.


Are Silencers Legal in the United States?

At the federal level, the ownership and possession of suppressors are regulated under the National Firearms Act (NFA).

To legally own a suppressor, individuals must go through a detailed application process, which includes paying a federal tax, submitting fingerprints and photographs, obtaining approval from their local chief law enforcement officer, and undergoing a background check. Once approved, individuals can legally purchase and possess suppressors.


While suppressors are legal at the federal level, their legality varies from state to state. Currently, 42 states allow the private ownership of suppressors, but some states have specific regulations or restrictions.

California, Hawaii, Illinois, New York, New Jersey, Massachusetts, Rhode Island, and Delaware have outright bans on civilian ownership of suppressors. Additionally, the District of Columbia also prohibits their ownership.

Suppressors became subject to increased regulation in the United States with the passage of the National Firearms Act in 1934, which imposed strict regulations on a range of firearms-related items, including rifle suppressors. In recent years, there have been efforts to ease restrictions on suppressors in some states, with some legalizing their use for hunting and recreational shooting.

This article was updated in conjunction with AI technology, then fact-checked and edited by a HowStuffWorks editor.


Frequently Answered Questions

Do gun silencers really work?
Yes, gun silencers work by reducing the noise of the gunshot.
Is it legal to purchase a gun silencer in the United States?
It is legal to own a silencer in 42 states. However, California, Hawaii, Illinois, New York, New Jersey, Massachusetts, Rhode Island and Delaware have outright bans on civilian ownership of suppressors. They are also prohibited in the District of Columbia.