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ATF Open Letter: Some “Solvent Traps” Classified as “Firearm Silencers”

Written by Austin Alterio


November 21, 2023


ATF Open Letter: Solvent Traps

The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) recently examined devices commonly marketed as “solvent traps” and has determined that some of them are “firearm silencers” as defined in the Gun Control Act (GCA) and as defined in the National Firearms Act (NFA).

“Solvent traps” are marketed as devices that attach to firearm barrels to catch excess solvent used when cleaning firearms. ATF has not classified any device as a “solvent trap,” because that term does not exist in the relevant Federal statutes or implementing regulations.

However, ATF has classified numerous devices as “firearm silencers,” even though they are marketed as “solvent traps.”

The test for whether an item is a silencer is not the label a manufacturer or retailer applies. Rather, it is the way the statute written by Congress applies to the item.

Both the GCA and NFA regulate “firearm silencers.” The term “firearm muffler or firearm silencer” is defined under 18 U.S.C. § 921(a)(25) and 26 U.S.C. § 5845(a)(7) 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 use in assembling or fabricating a firearm silencer or firearm muffler, and any part intended only for use in such assembly or fabrication. 

Some of the devices commonly marketed as solvent traps have been determined to meet the definition of “firearm silencer” because they have the objective design features and characteristics indicating that the device is “for” reducing the report of a portable firearm. Although solvent traps are generally marketed as having an intended use other than as a silencer, e.g., filtering firearm cleaning solvent, that is not determinative under the statute. ATF mustconsider a device’s objective design features, including the uses of which a part is capable, aspart of the inquiry into whether the device is a silencer. See, e.g., Sig Sauer v. Brandon, 826F.3d 598 (1st Cir. 2016).

For example, holes (or marks indicating where holes should be drilled) that allow the passage of a projectile are clear indicators that the device or component parts may be properly classified as “firearm silencers,” because this allows the propellant gasses to expand and cool. By contrast, a hole serves no purpose in collecting solvent or debris and is actually contrary to the purported use of a “solvent trap.” The presence of indexing marks to drill a hole is not a prerequisite to classification as a “firearm silencer”; it is merely an example of such evidence. 

Other such characteristics may include baffles, spacers, ported inner sleeve or tube, expansion chamber, end caps, and dampening material, depending on the particular design of the device. While increasing the effectiveness of a firearm silencer, these same objective design features offer no advantages in collecting or filtering cleaning solvent. 

Solvent Trap ATF Open Letter - Firearm Silencer

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.” 

In fact, Congress explicitly chose to regulate a combination of parts intended for use in assembling or fabricating a firearm silencer and “any part intended only for use” in assembling or fabricating a firearm silencer. See 18 U.S.C. § 921(a)(25). Accordingly, a silencer part intended only for use in assembling or fabricating a firearm silencer is, itself, regulated as a “firearm muffler or firearm silencer” under both the GCA and NFA. For example, a silencer end cap falls under the federal definition of a “firearm silencer or firearm muffler” at 18 U.S.C. § 924(a)(25) and therefore it is regulated as a silencer under the GCA and NFA even when the silencer end cap is individually sold and transferred and not installed as a component part of a silencer. Therefore, the importation, manufacture, and transfer of such silencer parts must comply with the provisions of the GCA and NFA. 

Furthermore, Federal courts have held a device can be a silencer for the purposes of 18 U.S.C. § 921(a)(25) even if it is not operable in its current state. These courts have held that the Federal statute does not limit the definition of a silencer to “a device that silences, muffles, or diminishes.” See United States v. Carter, 465 F.3d 658 (6th Cir. 2006); United States v. Rose, 522 F.3d 710 (6th Cir. 2008); United States v. Rogers, 270 F.3d 1076 (7th Cir.2001); United States v. Syverson, 90 F.3d 227 (7th Cir. 1996). This is consistent with Congress’ intention to regulate all devices “designed and intended” to be used as silencers, not just those devices that are currently in a completed state, such that they will reduce the report of firearms when attached. 

The “solvent trap” devices that are silencers cannot be registered in the National Firearms Registration and Transfer Record (NFRTR) by an individual purchaser. Specifically, the NFA, 26 U.S.C. § 5841, mandates that the “manufacturer, importer, or maker shall register each firearm he manufactures, imports, or makes.” Therefore, it is unlawful to manufacture “firearm silencers” for transfer to individuals who have applied to make that same firearm by filing an ATF Form 1. These firearms have not been registered by the manufacturer by the close of the next business day after manufacture in compliance with federal regulation. 27 CFR 479.103. An NFA firearm that has already been made/manufactured in violation of the NFA may not be registered by the current possessor. 

Both the GCA, 18 U.S.C. § 922(l), and NFA, 26 U.S.C. § 5844, generally prohibit the importation of “firearm silencers”, except under certain authorized exceptions and with required licensing and registration.1 

Current possessors of these purported “solvent traps” that are silencers are encouraged to contact ATF for further guidance on how they may divest possession. If you are uncertain whether the device you possess is a “firearm silencer” as defined by the GCA and NFA, please contact your local ATF Field Office. You may consult the Local ATF Office’s webpage for office contact information. 

1 See also 26 U.S.C. §§ 5871 (penalty provisions for violation of the NFA) and 5872 (seizure and forfeiture provisions of the NFA). 

Read the ATF Open Letter PDF here.

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