When the topic of a “Hard Use” or “Duty Use” suppressor comes up, often the conversation becomes about the materials used and the construction of the suppressor. While the construction of the suppressor itself is a key consideration, there’s one part that has been largely relegated to an afterthought despite being a key component: how the suppressor mounts to your barrel. 

Irregular Design Group (IDG) saw this problem and has addressed it with a novel and notable approach, but how does the mouthful of a name suppressor stack up in a field chock full of options?

The Hesychia SIXK sports a name based on Orthodox Christianity. Its namesake, “Hesychia,” is Greek for stillness or silence, referring to a practice of peace, tranquility, and silence that Eastern Orthodox monastics pursue. With suppressor names often being aggressive analogies for their use, this choice is an interesting and welcome change of pace. The SIXK portion refers to a welcome design philosophy from Irregular Design Group, their focus on making the best K or Kurz suppressor. 

This means squeezing as much suppression out of a suppressor that is demonstrably smaller than many of its full-size brethren. K-cans, as they are colloquially known, are not new, but the focus on that form factor for a product line is a new approach. K suppressors sport several benefits. In 2018, I was fortunate to attend the first Shooters Symposium, and none other than Chuck Pressburg changed the way I approached suppressors. I was shooting a Modified Navy Drill being run by Steve Fisher and dropped a shot going from prone to kneeling. 

That took me out of the running for the drill win, and after witnessing my failure, Chuck made a simple statement. “You know, if you had a 14.5” barrel with a K can, it would be the same length as that 11.5” with a full-size can and you’d have better ballistics and about the same suppression.” Ever since then, I’ve been chasing that ideal K suppressor. The SIXK is a serious contender.

The suppressor itself is manufactured out of 718 Inconel using laser powder bed fusion with an internal gas flow management system, reducing backpressure while still producing solid sound and flash suppression. Available in Black, Flat Dark Earth, OD Green, and a raw finish, the exterior sports a topographic-esque pattern that gives a reasonable amount of added grip purchase. 

The vents at the front of the suppressor are cleverly recessed, allowing gas flow forward after spinning it several times internally. The SIXK sports asymmetrical baffles and an annular region, which is two concentric circles breaking up the hot gases as they travel internally, producing a dramatically reduced signature for a suppressor of its form factor. At only 15.5 oz. with an outside diameter of 1.65” and a length of 5.125” added to the length of the barrel with the mount, it’s also right there with the rest of the market, if not better.

What makes the suppressor truly unique isn’t the suppressor itself; it’s the mounting system. Taking inspiration from the venerable Yankee Hill mounting system, the SIXK takes it a number of steps further. First, the muzzle device, which is explicitly designed as a suppressor host, is manufactured in the same way and out of the same 718 Inconel. 

A challenge many users face as they run suppressors hard is that different materials behave differently under heat and stress. We commonly see muzzle devices manufactured from stainless steel, which, when it interacts with Inconel or Titanium, commonly found in the manufacturing of suppressors, creates inconsistency. 

This can lead to suppressors locking up, tolerance issues, or, in the worst case, accuracy challenges. Irregular Design Group recognized this quandary and addressed it with a fundamental design change that takes suppressors to the next step in their evolution. There’s even lore associated with the design of the muzzle device. There’s even lore associated with the asymmetric diamonds around the crown of the suppressor. 

The designer hails from the storied history of an 0321 Reconnaissance Marine, where he spent his entire career with 1st Recon Battalion. While in selection, 1st Recon was dominating in the Helmand Province, earning the moniker “Black Diamonds” from enemy combatants who could easily identify their black Norotos NVG mounts contrasted against the tan helmets. 1st Recon Battalion later adopted that callsign, which are what those shapes are a tribute to, as well as there being six to signify the standard size of a Recon Team.

Beyond the material choice, IDG  introduced what they call the patent-pending Hesion Bow Mounting System. Revolutionary is a highly overused word; however, this design is something special. First, six rounded flexure pawls work as a bi-directional ratchet system, relying on the tensile strength of the Inconel to apply pressure onto the muzzle device's scalloped ring. 

The level of deflection, shape of the pawls, and the scallops of the muzzle device were designed to wear into the optimal level of retention, not wear out to failure due to dissimilar materials, hardnesses, and mechanical wear. While the Hesion Bow system is strong enough to prevent counter rotation from shooting without being fully tightened, the primary locking system is the pairing of a massive American Buttress thread and the .25” long 15-deg tapered alignment/sealing face. 

For many suppressor mounts, a thread and taper in various forms is considered standard, but they still loosen while firing or get stuck in some instances. IDG's approach was not to just improve on threaded taper mount, but provide an integrated, redundant locking system that only adds .5 oz to the suppressor with no little parts or springs. 

Two is one, and one is none.  As an example, I screwed the suppressor onto the mount and ran two full magazines as fast as a forced reset trigger allowed. While the suppressor was smoking after the second magazine, the painted witness mark on top of it didn’t move a hair. 

Using remarkably consistent 77-grain Match rounds from Scorpion Ammunition out of Tempe, Arizona, I was able to verify on a Criterion 14.5” and 12.5” that the SIXK returned to zero consistently. 

The BRVO Tactical Sierra 1 Site provided an excellent environment to test the suppressor's performance with a combination of arid conditions, moon dust, and challenging shooting environments. The 12.5” setup performed remarkably well with the Surefire Optimized BCG exclusively available from Primary Arms. 

Many jokes have been made over the centuries about size mattering. Based on experience, that is especially true when it comes to what you hang off the front of your rifle. Whether it be 6mm ARC, 5.56, or .223, you will be hard-pressed in the current environment to find a suppressor that exceeds what the Hesychia SIXK offers. In the quest for an ideal K-can, seemingly out of nowhere, the crew at Irregular Design Group has stepped up to the plate and knocked it out of the park. 

One can only hope that the rest of the suppressor industry takes note of this design and starts the shift into paying more attention to muzzle devices and mounting as a system rather than an afterthought. For those of us who have had to remove suppressors with a strap wrench, or worse, shoot them off the end of your rifle, these experiences should and need to be a thing of the past. The SIXK and its future design interactions are a solution and more. 

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