Gun Suppressors: How They Work and How They’re Made

Firearm suppressors (also called silencers; both terms are correct) are likely the most recognized gun accessories, yet are among the most maligned and misunderstood. Shortly after Hiram Percy Maxim invented the first gun silencer in 1902, popular culture tells us that this firearm accessory became the favorite tool of mobsters and other criminals.

In this article, we’re going to give you the basics of silencers, provide some insight into how they work, and look into some of the most common types of suppressors and how they’re made today.

To this day, nearly every movie or TV show involving firearms, spies, and/or hitmen will include some footage of a suppressor, usually with an unrealistic portrayal of how effective they are. These scenes often make suppressors seem so effective that you could have a gunfight with silencer-equipped pistols while strolling through a crowded subway station and nobody would notice. It’s inaccurate and absurd, but this kind of portrayal serves to deepen the myths and misinformation around gun suppressors.

Video: Silencer vs Suppressor - What's the Difference?

In the most simple terms, a suppressor is essentially a muffler for a firearm. Similarly to how an automobile muffler reduces the very loud sound produced by the expanding gases of an internal combustion engine, a firearm suppressor reduces the very loud sound produced by the expanding gases of a firearm (or even an air rifle). A car’s muffler contains, redirects, and muffles the gases and sound waves exiting an engine, and a firearm suppressor contains, redirects, and suppresses the high-pressure gases and sound waves exiting the muzzle of a gun.

Image Courtesy of AAC

A suppressor works by containing, slowing, cooling, and redirecting the hot, high-speed gases exiting a firearm’s muzzle when it is fired. The most common design resembles a cylinder on the outside (which is why silencers are sometimes informally called cans), that is threaded directly onto the barrel or attached to a muzzle brake, flash hider, or suppressor mount that is installed onto the barrel. Inside the can or cylinder is a series of partitions, vanes, baffles, or other barriers that are designed to let the projectile/bullet through, but which deflect, redirect, cool, and contain the gases that contribute to the loud noise of a firearm’s report.

Note that a significant portion of the sound of many firearms is the supersonic crack of the projectile breaking the sound barrier, and the vast majority of suppressors can do nothing to mitigate that crack. However, some suppressors historically used in espionage or special military groups incorporate one or more flexible disks called wipes (typically made of wax, rubber, neoprene, leather, or polymer) that are sometimes perforated or pre-cut to allow the bullet to easily pass through, but are potentially capable of slowing the bullet to below the speed of sound to eliminate the supersonic crack, as well as more fully sealing around the bullet to contain the expanding gases. This type of suppressor can be extremely quiet (relative to other suppressor designs) but the wipes quickly wear out, after as few as 2 or 3 shots in some cases, so they are not practical for civilian/recreational use. Nearly all modern suppressors intended for commercial or general military sale are wipeless types, where the bullet doesn’t ever touch any surface of the suppressor at all.

Some suppressors support the practice of being used wet, where a liquid or gel material is added to the interior of the suppressor to further absorb and disperse the pressure and heat of a firearm’s shot. This can make a silencer even quieter. Commonly, suppressor owners often use something like wire-pulling gel as an ablative medium, or many people simply use water.

Image Courtesy of AAC

Your hearing can be permanently damaged by a single close-range exposure to a loud noise over 140 dB, or by prolonged exposure to noises as low as 80-110 dB. Within enclosed spaces (like indoor shooting ranges or your house) the potential for damage increases. The more you shoot, the greater the potential for permanent hearing loss. Suppressors are important safety features on many firearms.

Another benefit? In some cases, suppressors can help reduce the punishing recoil of large, powerful firearms. The weight of the suppressor helps a little, but trapping that explosive gas against the internal surfaces of the suppressor can also act to reduce felt recoil, and the shocking muzzle concussion of an unsuppressed shot is also reduced or removed, which helps further.

Additionally, some firearms are more accurate with a good suppressor fitted. It may seem illogical or implausible, but ask anyone who has shot a lot of firearms suppressed and unsuppressed and they’ll likely tell you that some guns, with some loads, are much more accurate when using a suppressor. This may have to do with barrel harmonics, the reduction/dispersion/slowing of explosive gas on the bullet as it exits the muzzle, or both.

Another benefit of suppressor use is that the sound of gunfire is less annoying to surrounding landowners, neighbors, or others in the outdoors. A shooting range or parcel of hunting property where people use suppressed firearms is much less likely to be shut down due to public outcry.

For military and tactical purposes, a good suppressor can reduce the sound and flash signature of a firearm so it’s more difficult for an enemy to determine exactly where gunfire is coming from. Suppressors can help squads maintain communication better when clearing rooms since suppressed gunshots are much less punishing to the ears and nervous system of the user and any squad members than unsuppressed shots.

Image: SilencerCo Hybrid 46

Generally speaking, there have historically been two main types of silencer design: baffle stack or monocore. (3D-printed suppressors are also becoming wildly popular, but the designs can generally be termed monocore in principle. More on that below.)

In a baffle stack suppressor, several separate sections called baffles, usually generally cylindrical/cone-like in shape, are stacked atop one another to create a series of partitions and passages that helps disperse and redirect the expanding gases of a gunshot. These baffles are either slid inside an outer tube or sleeve, with the end caps threaded or welded on, or in some more advanced designs, the outer skirts of the baffles themselves are welded together precisely to form the tube of the suppressor (except in this case there is no separate outer tube). This type of baffled suppressor can be much lighter and theoretically stronger than a traditional design with separate baffles and an outer tube. SIG SAUER popularized this type of suppressor design a few years ago and transformed the industry, but now the 3D-printed approach is likely to become the gold standard.

Video: Sig's NEW 3D Printed Silencers: The SLH, SLX, and MOD-X

A monocore type suppressor, rather than utilizing several different, stackable baffle sections, takes advantage of advanced machining techniques to create a single internal suppressor core, running most of the length of the outer tube, that can be inserted and removed as a single unit, which eases disassembly and cleaning in the case of user-serviceable suppressors and can reduce weight and increase effectiveness for sealed suppressors. Multi-axis CNC machining can create shapes and designs in a monocore format that can’t be replicated by any baffle-stack design. This can result in a quieter suppressor, a lighter suppressor, and/or a suppressor that’s more suitable for multi-caliber use since it can more easily be cleaned.

Often, rifle suppressors are considered self-cleaning as long as jacketed or fully copper bullets are used, while handgun or rimfire suppressors need to be cleaned occasionally to remove lead buildup, depending on the ammunition.

Both baffle-type and monocore suppressors come in user-serviceable designs with removable end caps for disassembly, cleaning, and baffle/core replacement if needed, as well as sealed or non-serviceable, fully welded or printed types. Sealed suppressors are typically welded or printed without removable end caps, so if you need anything internally replaced, you’ll need to send it back to the manufacturer to be cut open, repaired, and re-welded, or replaced if things look bad enough.

3-D printed silencers

The hottest new trend in suppressor manufacturing and design over the past few years is 3D-printing, also called additive manufacturing. Rather than starting with an outer sleeve or tube into which you slide your baffles/monocore, or welding multiple skirted baffles into a tubeless suppressor, a 3D-printed suppressor is effectively welded from the base up in thin layers utilizing powdered metals and high-output lasers guided by sophisticated computers.

Image Courtesy of The Firearm Blog

In additive manufacturing, you start with a powdered metal alloy such as titanium, Inconel, stainless steel, or other material, and the computer-guided lasers print or weld the desired shape, fusing the powder into a solid metal surface where the laser hits it, and then the excess powder is collected and reused. A suppressor made in this way can include internal passages, vanes, shapes, and geometries that are impossible to make using baffles or even multi-axis CNC subtractive manufacturing (where you start with a billet of metal or other material and cut away the extra).

As a result, today’s advanced-alloy 3D-printed suppressors can feature much lower back pressure (the gases flowing back through the barrel into the action of the gun), muzzle flash, heat retention, and weight compared to traditional designs.

There are also 3D-printed monocore and baffle designs, usually for economy’s sake, but generally, a 3D-printed suppressor is not intended to be disassembled or have its components replaced, since they are typically printed all in one piece. You’re going to see many more companies investing in this technology over the coming years (one additive manufacturing machine capable of printing a suppressor from appropriate alloys runs about $500,000 to over $1M).

Image Courtesy of Gemtech

Yes, with some caveats and qualifications. At the time of this writing, silencers are legal for ownership by non-prohibited persons under federal law in all 50 states but are only legal under state law in 42 states. Silencers or suppressors are considered NFA items, meaning they fall under the purview of the 1934 National Firearms Act and Title II of the Gun Control Act of 1968 which regulate, on a federal level, items such as machine guns, short-barreled rifles, sawed-off shotguns, destructive devices, suppressors, and certain other firearms called any other weapons with certain characteristics deemed to be worthy of additional scrutiny and taxation.

These items can’t be transferred (sold, bought, or given) or manufactured without prior federal approval via a special business/manufacturing license or paperwork filed with the Department of the Treasury’s Bureau of Alcohol, Tobacco, and Firearms and the purchase of a special tax stamp for each item.

Image: SilencerCo Octane Series

Note: simply threading or taping a hollow container such as a plastic soda bottle to the muzzle of a firearm may have limited effectiveness in lowering the sound signature, depending on the gun and the cartridge being fired. However, in the USA, this is a felony, since you are (according to the law) manufacturing a homemade silencer without a license. Don’t do it. The penalty for manufacturing a suppressor without a license is $10,000 for each offense, plus a minimum of 27 months up to 10 years in federal prison… and the ATF has no sense of humor.

Besides, a well-made suppressor is orders of magnitude more effective and durable than improvised silencers.