For decades silencers have consisted of a single tube with internal baffle sections sandwiched between two endcaps, one designed to mount onto the host firearm the other designed to be the business end. However a chain of historical, technological and economical events (along with the work of some big brains) have allowed manufacturers to get creative with overall silencer design. Branded as Modular Silencers, companies have developed ways to build suppressors that can be broken down into smaller sections, creating a variable length device.

One of the keys to legality of these “multi-length” silencers is that, no matter what configuration is used, the combination of the original parts can only be assembled into one device at a time. Meaning the “extra parts” remaining after assembly cannot be assembled into a second suppressor.

With all of the modular models of suppressors hitting the market, the ATF is set to make a determination on the the rules/regulations surrounding these configurable cans. At the top of the list will surely be ‘spare parts’ which you probably all know by now are not allowed without paying additional NFA taxes (silencer parts = silencers). For example, a manufacturer can’t sell you extra baffles without the need for an ATF Form 4 transfer application and you having to pay $200 for each individual part.

By design, modular silencers do not have spare parts; if used in a short configuration, there may be unused parts, however the same set of circumstances can be crated with a traditional silencer and removing internal baffles.

Also, sure to be included in the official discussions will be the length and caliber values as noted in the registry. These measurements need to be specific and cannot (currently) include variable length ranges and multiple calibers designations.

A recently expired patent filled by Heckler & Koch over twenty years ago examined the application of modular silencers. (Much thanks to Q Engineer Ethan Lessard for the technical guidance). To my knowledge, H&K never sold a modular firearm suppressor under this patent. But, with it’s expiration, numerous companies have brought configurable suppressors to market.

FIELD OF THE INVENTION This known silencer consists of an attachment piece that can be attached to the muzzle of a weapon, of an end piece, and, in between, of a series of rings that are successively placed in a centered manner, and that form the outer wall of the silencer, and between each of which a dividing wall featuring a firing opening is set, thus forming successive chambers. The individual rings differ from each other in terms of their length so that only one single, specific ring is associated with each longitudinal segment of the silencer. It is known from FR-8-323 574 (HUMBERT) that the structural members that constitute the individual chambers can be arranged within a common outer barrel. *** Overall, a silencer should always be as short as possible. This is because it increases the total length of the firearm that has been painstakingly shortened by other design means, and it furthermore adds weight to the muzzle, thus impairing the weapon’s balance. Although different weapons may have the same caliber and muzzle shapes, it is still necessary to manufacture and stock many silencers with different lengths, in order to meet all requirements. This heavy expenditure is a disadvantage. The invention’s task is to improve the initially mentioned, known silencer in such a way that it can be adapted to the particular requirements with minor effort. The invention solves this problem by means of the object of claim 1, which means an object in which the features of this class are combined with the other features, i.e., each chamber part is attached according to a modular principle directly to the adjoining chamber part, and the outer walls of the successive chamber parts form the outer wall of the silencer. The successive outer walls of the chamber parts thus form the silencer’s outer wall. The jacket tube necessary for the known silencer is thus eliminated. SUMMARY OF THE INVENTION In the silencer according to the invention, the individual chamber parts can be connected to each other, to the attachment piece, and/or to the end piece, for instance, by resistance welding. Parts with a non-circular cross-section also can be connected to each other in this way.

Major American companies with modular silencers:

Joshua Prince of the Prince Law Firm and Blog recently posted the news about the upcoming ATF ruling/determination/guidance while attending the NSSF/FAIR Trade Group’s 16th Annual Firearms Import/Export Conference at a round table discussion with the Firearms and Ammunition Technology Division (FATD):

Second, in relation to modular silencers, FATD acknowledged that it currently has pending before it a request for determination of legality from a modular silencer manufacture. Division Chief Griffith and Branch Chief Curtis raised concern over the determination request and the issues that must be addressed, including whether modular silencer are legal, when reduced in size. In essence, the concern stems from there arguably existing additional silencer parts that are not part of the modular silencer’s configuration, when it is reduced in length. In the event that ATF would rule that modular silencers are generally lawful, it raises a plethora of other issues, including where the markings must be placed (which is interrelated to ATF’s currently pending rulemaking: ATF-29P) or whether such silencers would require either specific location markings or multiple markings. Although ATF was reluctant to state whether these determinations would be in the form of “policy determinations,” “guidance” or “formal rulings,” and stated that it could not provide an exact timeframe for these determinations, it was stated that they are overdue and should be expected in the very near future. Read more here.

And, because their is a proposed rule change regarding the location of markings on silencers that could have an effect on modular devices, here’s a link to TFB’s coverage from last year.

So, what is the future of modular silencers? Who knows.

Would I be concerned with buying any of the current configurable cans on the market? Nope.

Even if the ATF decides a rule change is required, silencers already in the hands of shooters should be grandfathered and users not required to pay additional tax. Besides, I don’t see the ATF making a dramatic ruling against modular silencers at the moment – ownership is at historic highs with more and more silencers in the hands of new shooters every year and at least some of ATF’s leadership want to see them removed from the NFA entirely.

Exciting times.

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[Author] – Additional information added 8/12/2017 from the American Suppressor Association:

STATEMENT REGARDING POTENTIAL ATF DETERMINATION ON MODULAR SUPPRESSORS