Hesychia SIXK Suppressor Technical Overview

Designed by USSOF veterans, the Hesychia SIXK suppressor optimizes performance in the compact, under-six-inch category for 5.56mm NATO and 6mm ARC supersonic rounds. Through innovative gas management, monolithic Inconel 718 construction, and the patented Hesion Bow mounting system, it delivers effective sound and flash suppression, durability, and ease of use.

Design Philosophy

The Hesychia SIXK was engineered to overcome the limitations of K-series suppressors, which often struggle with sound suppression and low-backpressure balance for high-velocity 5.56mm and 6mm ARC rounds due to their compact size and lack of volume for managing excessive gas pressure. By prioritizing early gas control and high-flow dynamics, it achieves a balanced, durable system that minimizes audible and visible signatures without the need to add weight or length to achieve.

• Compact Performance: Delivers exceptional tone and sound suppression in a sub-six-inch envelope typical of K-series designs.

• Supersonic Optimization: Balances gas disruption and flow to prioritize a deep tone and low back pressure over total decibel reduction.

• Redundant Retention: The Hesion Bow system provides a positive locking taper with integrally redundant mechanisms to prevent the suppressor from coming loose from high firing schedules.

Gas Management System

The Hesychia SIXK employs a dual-path gas management system, splitting propellant gas into an external annular region and a central baffle stack to prolong off-gassing and reduce pressure fields, enhancing sound and flash suppression.

External Annular Region

The blast baffle captures initial gas, diverting it into an annular channel with eight sealed, variable-pitch helical chambers. Gas is redirected 180 degrees back toward the barrel, then spun down the suppressor’s axis into a final chamber, where shields enforce 90-degree turns to prevent direct venting.

• Blast Baffle Efficiency: Controls initial gas expansion to minimize rapid acceleration.

• Variable-Pitch Helix: Transitions from a loose to a tight twist, maximizing surface area and slowing gas via vectoring.

• Shielded Final Chamber: 90-degree redirects reduce pressure spikes, contributing to a lower tone than traditional low back pressure suppressors.

• Diamond-Patterned Blast Chamber: Doubles surface area for gas disruption and maximal abrasion resistance.

Annular Region Defined

An annular region is a ring shaped area bound by two concentric circles. It's essentially the area between the outer and inner circles, in this case, the outer shell and the inner core of the suppressor. This is a common technique employed by most additively manufactured suppressors in order to route excess blast chamber gas away from the central core, leaving lower pressure gasses to interact effectively with more abrupt disruptive geometries like baffles. While most suppressors leave this region vacant to encourage lower back pressure, the Hesychia SIXK does the opposite without increasing back pressure. If applied properly, gas that has been routed into the external annular region can be reintroduced back into the main core and exit out of the central bore without adding excessive pressure. This allows for a deeper tone and lower decibel levels than other suppressors that vent blast chamber gas directly to the atmosphere through the annular region.

Central Baffle Stack

Gas in the central bore flows through seven asymmetrical baffles, interlocked to maximize surface area and force differential volumes of gas diverting. A secondary bypass between baffles diverts gas into a deep, shielded chamber, balancing pressure during rapid fire while also reducing the amount of gas travelling down the central bore.

• Asymmetrical Baffles: Allow for a denser baffle core while also reducing the resonant gas stacking of symmetrically spaced and patterned baffles.

• Secondary Bypass: Bleeds gas into the final chamber at an angle to disrupt external annular gas entering from a different orientation.

• High-Flow Dynamics: Maintains performance under heavy firing schedules by avoiding gas accumulation through large ports. This also prolongs ports from clogging from carbon deposits between longer cleaning intervals.

Universal Host Platform

The Hesychia SIXK was designed to run on a wide range of host platform configurations and gas systems. From 10.3” barrel pistol length direct impingement gas systems to 16” short-stroke piston gas systems, the lack of additional backpressure from the suppressor removes the requirement for adjustable gas blocks for most platforms.

Flash Suppression

The Hesychia SIXK minimizes primary and secondary flash through internal gas combustion and a minimalist front-end geometry, preventing stoichiometric conditions that cause bright secondary flash.

• Internal Powder Burn: The final chamber’s large cavity and 90-degree gas mixing burn powder internally, reducing primary flash.

• Shielded Nose Cap: Three small slots with 90-degree shields vent gas laterally, minimizing secondary flash and excess pressure exiting the central bore.

• Low Back Pressure: Avoids large coaxial ports, reducing rapid atmospheric saturation for enhanced flash and sound control.

Material Selection and Manufacturing

Additively manufactured via laser powder bed fusion (LPBF), the Hesychia SIXK and its muzzle device use Inconel 718, ensuring durability and thermal stability under extreme conditions.

• Inconel 718: Maintains strength and dimensional stability at high temperatures, resisting thermal cycle fatigue.

• Hollow Muzzle Device: Reduces weight and provides access to the back face of the taper to encourage faster cooling for ease of suppressor removal after shooting.

• Fillet Corners: All internal edges radiused edges prevent stress concentrations, enhancing longevity.

• Camouflage Pattern Heat Sink: Outer surface of the suppressor has 3D camouflage impressions to increase surface area and thermal dissipation.

• Camouflage Pattern Weight Savings: This also is a weight saving technique that saves over 1.5 ounces from the total system weight, without negatively impacting the integrity of the outer casing.

• Matched Thermal Properties: Identical materials prevent thermal locking, unlike 17-4 stainless steel alternatives.

• Monolithic Construction: LPBF enables complex geometries, such as the variable-pitch helix and diamond arrays.

Hesion Bow Mounting System

The patent-pending Hesion Bow system is the combination of a few distinct features that create an integrated, robust, lightweight redundant locking system with no mechanical assembly or multiple failure points.

• Flexure Interface: Six flexure pawls extending from the suppressor base and 32 index grooves radially patterned around the muzzle device which results in constant tension applied to every angled surface. Eliminates backlash and ensures active tension application when taper lock is set.

• American Buttress Thread: Left-hand 1.125-inch by 8 TPI thread transfers power unidirectionally, requiring only 15 foot-pounds of input torque that applies 1,700 ft. lbs. of compressive force on the taper interface.

• 15-Degree Taper: A linear distance of .25” lock-up surface with 15 degrees included angle ensures a mechanically advantageous interaction between the suppressor and muzzle device.

• Obtuse Engagement Angles: Flexure pawls and muzzle device groove geometry minimizes wear due to no sharp angles, which eliminates stress concentrations that could wear down prematurely like typical sharp toothed uni-directional ratchet systems.

• Redundancy: Prevents counter-rotation and carbon locking, with ample thread root spacing if carbon bypasses the taper seal. Flexure pawls also actively input more force than the counter rotation force of vibrations and gas flow. This allows the suppressor to still function even if the system isn’t fully locked and sealed, which prevents catastrophic failure such as a suppressor ejecting from the muzzle device.

• Lightweight: Adds only 0.5 ounces, compared to 3-5 ounces for multi-part HUB systems.

• Integrated Wrench Flats: Corners of Hesion Bow covers are flattened to provide discrete wrench flats for worst case scenarios where the force to overcome the removal of the suppressors exceeds what could be done by hand.

Muzzle Device Design

The Hybrid Flash Hider is optimized for suppressor integration, functioning as both a flash hider and muzzle brake through complex LPBF-enabled geometry.

• Equidistant Gas Array: Diamond-patterned ports vector gas off-axis, feeding the annular region for enhanced early gas management.

• Dual Functionality: Vertical features reduce recoil, while radial distribution minimizes secondary flash.

• Thermal Compatibility: Inconel 718 matches the suppressor’s properties, preventing thermal locking.

• Hollow Structure: Facilitates cooling to mitigate rare thermal coupling.

Specifications

The Hesychia SIXK is a compact, lightweight suppressor designed for versatility and durability in demanding environments.

• Caliber Rating: 6mm ARC, 5.56mm NATO

• Overall Suppressor Length: 5.72” / 145mm

• Muzzle Device Length: 2.125” / 54mm

• Length Added: 3.625” / 92mm with suppressor installed; muzzle device adds 1.5” / 38mm to barrel. The entire assembly adds 5.125” / 130mm length to the end of a barrel

• Diameter: 1.65” / 42mm

• Weight: 15.5 ounces / 440 grams (suppressor), 3 ounces / 85 grams (muzzle device).

• Material: Inconel 718.

• Construction: Laser powder bed fusion (LPBF) and Machine Finished

• Finish (Suppressor Only): High Temp Cerakote® or raw

• Finish (Muzzle Device Only): Black PVD

• Mount: 1.125”-8 left-hand American Buttress Thread (patent-pending), Hesion Bow (patent-pending)

• Barrel Restrictions: None

• Full Auto Rated: Yes

• Internal Taper Angle: 15 degrees

• Decibel Reduction Average (At ear): -30 db +/- depending on ammo and host weapon

• Decibel Reduction Average (1m Left): -25 db +/- depending on ammo and host weapon