A silencer, or sound suppressor, is a device that helps dampen a firearm’s sound signature, or report, and eliminate its muzzle flash, making it harder to determine where a shot originated. The devices work like car mufflers, allowing the hot gases that follow a bullet down the firearm’s barrel to expand and cool down before hitting the air outside of the gun, reducing the loud “pop” that normally comes with every gunshot.
After being invented in the early 1900s, silencers were quickly used in high-profile crimes, leading Congress to regulate silencers through the National Firearms Act (NFA) in 1934 along with other dangerous weapons, including machine guns and short-barreled rifles and shotguns. Since 1934, civilians interested in owning a silencer have had to submit an application along with their fingerprints and a passport-style photo, and pay a $200 tax stamp, before undergoing an enhanced background check. Only after being approved by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) can someone take possession of an NFA item, such as a silencer.
With its $200 tax stamp — prohibitively expensive in 1934, though the cost has never been raised or adjusted for inflation — the NFA application process was designed “to curtail, if not prohibit, transactions in NFA firearms.”
However, in recent years, a number of online retailers have offered “solvent traps” and “fuel filters” that are essentially unfinished, and untraceable, firearm silencers — much like the 80-percent frames and receivers used to build “ghost guns.” The products have similar features as silencers, including outer metal tubes, gas expansion chambers (or “baffles”) to help muffle the sound of gunfire, and even threading so they can be attached to barrels. The only thing required to transform one of these devices into a functional silencer is to drill out an end cap, allowing a bullet to pass through.
Retailers and proponents of these devices claim that solvent traps are merely cleaning accessories that, once attached to the muzzle of a firearm, will catch solvents that drip from the barrel as it is cleaned. Not only is this unnecessary — people have been cleaning firearms for decades without “solvent traps” by using an appropriate amount of cleaning solvent — but it does not explain why many of these devices come with sound-dampening baffles.
Along with marketing these items as cleaning accessories, some “solvent trap” retailers stated in the past that customers must receive ATF approval before drilling out the end cap and creating a complete silencer, strongly suggesting that the sellers know what customers can do with the products. But there is no mechanism to prevent someone, including criminals, from completing the silencer without receiving ATF approval.
THE ATF’S RESPONSE TO DIY SILENCER KITS
“Solvent traps” and other DIY silencer kits are an obvious attempt to circumvent federal regulations, which define silencers as “any device for silencing, muffling, or diminishing the report of a portable firearm, including any combination of parts, designed or redesigned, and intended for the use in assembling or fabricating a firearm silencer or firearm muffler, and any part intended only for use in such assembly or fabrication” (emphasis added).
Since 2017, the ATF has shut down several manufacturers and retailers for selling unregistered NFA items, including Darkside Defense, Diversified Machine, SD Tactical Arms, and Solvent Traps Etc., recognizing that those retailers’ “solvent traps” were indeed silencers. But the problem persists, as dozens of “solvent trap” and “fuel filter” retailers appear to still be operating online.
Between 2017 and 2021, law enforcement personnel recovered an estimated 9,130 privately made silencers and silencer parts, representing a 176.8-percent increase from the 3,298 recovered between 2012 and 2016, and several arrests have been made, including a Proud Boy supporter and January 6 rioter who was convicted of unlawful possession of unregistered silencers after purchasing three “solvent traps.”
The ATF has also denied NFA applications from people who have purchased “solvent traps” and attempted to register them as silencers retroactively. When the agency denied 850 such applications in early 2022, the agency stated that “it is unlawful for a person to make a silencer from a device or part that falls under the federal definition of silencer and was transferred to the applicant without complying with the tax, transfer, and registration requirements of the NFA.”
More recently, in November 2023, the ATF issued an open letter reiterating that some “solvent traps” are considered silencers, regardless of how they’re marketed, “because they have the objective design features and characteristics indicating that the device is ‘for’ reducing the report of a portable firearm,” such as sound-dampening baffles.
According to the ATF, “Over the years, many companies involved in marketing such ‘solvent traps’ have asserted that they are permitted to manufacture, transfer, or import these items because they are not yet ‘complete’ and therefore do not qualify as ‘firearm silencers’ under Federal law. However, this assertion is incorrect because a component of a ‘firearm silencer’ need not be fully functional before it is recognized as a ‘part intended only for use’ in assembling or fabricating a ‘firearm silencer.’”
Finally, the letter makes it clear that individuals cannot purchase one of these kits and then attempt to register the silencer with the ATF. “An NFA firearm that has already been made/manufactured in violation of the NFA may not be registered by the current possessor.”
INDUSTRY SUPPORT FOR SILENCERS MORE BROADLY
In addition to the growing problem of “solvent traps,” the gun industry has increasingly advocated for easier access to silencers. Groups like the NRA, American Suppressor Association, and National Shooting Sports Foundation, the firearm industry trade association, have pushed for bills that remove silencers from NFA regulations and allow them to be sold and transferred like any other weapon, as well as state laws relaxing silencer restrictions. These efforts are often branded as protecting the hearing of hunters and shooters, but earplugs and/or earmuffs are still recommended when using silencer-equipped firearms to prevent permanent hearing damage.
Silencers are just as dangerous today as when they were first invented, as evidenced by their use in mass shootings — like the 2023 Monterey Park shooting and the 2019 Virginia Beach shooting, where one survivor said the attacker’s suppressed firearm sounded like a nail gun, leading to more deaths: “If it was a regular gunshot, we would’ve definitely known a lot sooner, even if we would’ve had 30 or 60 seconds more. I think we could’ve all secured ourselves…all of us could’ve barricaded ourselves in.”