SILENCER SATURDAY #32: OSS Suppressors HELIX – Part 1

    Helix

    Welcome back to TFB’s Silencer Saturday, where guns are judged on the threads of their muzzle, not the color of their finish. After last week’s discussion on ammunition selection, baffle strikes and how to avoid similar mistakes, I jumped back on the proverbial horse and went out for more decibel metering (thanks again to Allen Engineering). I have to be honest, even after checking for concentricity, keyholing rounds and mount tightness, pulling the trigger on my first suppressed round was a little nerve racking. But with the OSS Suppressor HELIX HX-QD 556 securely mounted to the Dynamic Defense ROMEO upper, I proceeded to conduct science.

    SILENCER SATURDAY #32: OSS Suppressors HELIX – Part 1

    The reason we are breaking up the OSS HELIX review into two parts is that my battle rifle host, PTR91-K (G3K clone), ended up having FTF issues at the range. So the SilencerCo Saker 762 to OSS HELIX HX-QD 762 comparison is going to have to wait.

    This week we take a look at the HELIX 556 and do a comparison to the SureFire SOCOM 556 RC2. Why the SureFire to OSS faceoff? For one, the latest generation of SureFire’s 5.56 rifle silencer has been in wide circulation for a number of years and tends to be popular among both law enforcement and military specialized teams. If you have any time around suppressed ARs, you’ve probably heard a SureFire SOCOM in person.

    On the other hand, H&K was recently awarded a Department Of Defense contract for the Compact Semi Automatic Sniper System (CSASS) which had included an OSS suppressor (albeit a previous generation model). I reached out to OSS for updated CSASS information.

    The redesigned CSASS per OSS:

    After H&K was awarded, subsequent testing was done and the army began [making changes].  They wanted the rifle lighter, so they took a pound out of the barrel, and they went with a geissele M-lok rail (no surprise) to make it lighter.  They also learned afterwards that tucking a can under the rail was a bad idea if you wanted to run IR laser systems as the rail would get way too hot and damage equipment.  To solve this, they asked if we could produce a traditional flush-mount suppressor instead. 

    At that point, we worked closely with the Army in the development of the HX-QD 762 suppressor.  Here is the actual M110A1 rifle that is scheduled to ship next year: 

    Prior to SHOT 2018, I had my own personal reservations about OSS – not only when it came to some of the featured technologies, but also the perception of how the company might deal with criticism in the marketplace – my experience came from the back and forth between SureFire and OSS regarding failure testing here and here.

    But spending time with the OSS team at Industry Range Day at SHOT 2018 gave me pause – gone were the two part silencers with hexagon outer sleeves. But more importantly, the (recently reorganized) OSS crew seemed humble about possible past missteps and the way forward. And the latest generation of HELIX suppressors really did sound impressive.

    Specifications:

    The HELIX QD Muzzle device uses a tapered mounting surface ahead of the threads to keep fouling out of the system. OSS calls it ‘Torque Lock’ and I think it is great for suppressor mounts – no moving parts or pieces and the suppressor stays in place. At 3.67 ounces, the muzzle brake is definitely on the hefty side.

    At nearly 18 ounces The HELIX suppressor itself lands on the high side of the scale. However, there are definitely heavier silencers on the market. The total system weight is about 21.5 ounces.

    As a comparison, the SureFire SOCOM RC2 control silencer, muzzle device and mounting system weighs slightly less at about 20 ounces. SureFire uses a more traditional ratchet mount design.

    Theory

    OSS’s claim to fame is reduced back pressure and lower at-ear decibel numbers due to the ‘Flow-Through’ technology. The theory is fairly simple: instead of a system that redirects gas down the gas tube and barrel, OSS uses redirection and forward facing vents to force the gas out the muzzle.

    We’ve talked about similar designs such as Delta P Design’s Rattler and MP7 silencers, Next Gen 2 Defense silencers, and Q has just announced a new forward-venting silencer. Where OSS differs is the “baffleless” core that is specifically engineered to have no impact on the weapon system, reduce blowback and drop at-ear decibel numbers as opposed to muzzle readings. But how do we quantify “reduced” or “lower” dB?


    Metering from the OSS website:

    Signal Capture Hardware:

    Bruel & Kjaer Type 3052 Three Channel Input Module LAN-XI 102.4 kHz

    Sampling Rate: 262k samples/second

    Measurement locations:

    • Sensor 1: MILSTD 1 m (39”) left of muzzle 1.6 m (63”) up from ground.

    PCB 113B27 (SN-29177) Quartz sensing piezoelectric pressure sensor with = 1.0 µ sec rise time for center fire muzzle measurements.

    Maximum Pressure – 1kpsi

    Rise Time – ≤1.0 µ sec

    • Sensor 2: 38.1 cm (15”) for rifles or 48.26 cm (19”) for pistols to the rear of breech and 13.335 cm (5.25”) to the right of centerline of rifle/pistol.

    PCB 377A12 1/4″ (SN-119451) pressure, prepolarized condenser microphones for rear measurements (rim fire/center fire) and suppressed rim fire front measurements. Maximum Sound Pressure Level: 194 dB SPL.

    • Sensor 3: 38.1 cm (15”) for rifles or 48.26 cm (19”) for pistols to the rear of breech and 13.335 cm (5.25”) to the left of centerline of rifle/pistol.

    PCB 377A12 1/4″ (SN-119453) pressure, prepolarized condenser microphones for rear measurements (rim fire/center fire) and suppressed rim fire front measurements. Maximum Sound Pressure Level: 194 dB SPL.



    Shooting And Testing:

    As I mentioned last week, Dynamic Defense was nice enough to loan us one of their 18” ROMEO upper receivers for testing. It is outfitted with an adjustable gas block, which goes against the OSS mantra of no weapon modifications. Next week I’ll add additional hosts to the testing regimen for both the HX-QD 556 and 762.

    OSS Suppressors Helix HX-QD 556 Decibel Metering

    • Environment: 77 degrees; 95% humidity
    • Decibel Meter: B&K 2209 – A Weighted
    • Control Silencer: SureFire SOCOM 556 RC2
    • Host: Dynamic Defense 18” Romeo with adjustable gas block
    • Ammunition: 62gr Federal Fusion SP

    Meter Location: MILSTD Muzzle

    147
    145.6
    145.1
    143.9
    144.6
    145.3

    Meter location: Right Ear

    136
    135.1
    137.1
    138.3
    137.9
    137.8
    138.4

    • Environment: 77 degrees; 95% humidity
    • Decibel Meter: B&K 2209 – A Weighted
    • Test Silencer: OSS HX-QD 556
    • Host: Dynamic Defense 18” Romeo with adjustable gas block
    • Ammunition: 62gr Federal Fusion SP

    Meter Location: MILSTD Muzzle

    144.8 (failure to feed)
    142.4 (FTF) (1/4 turn open on SLR gas block)
    140.5
    139.2
    142.1
    141.5

    Meter Location: Right Ear

    136
    135.8
    136.1
    136
    135.1
    134.6
    134.7
    138.1
    136
    136.2
    136.5
    135.8
    137.7
    137.6
    140+ (bolt hold open)

    Observations & analysIs:

    Note: Decibel metering is a tricky prospect. These are my observations and I am not an expert. Someone else with the exact same setup could get different numbers on another day. Do your own research and decide which silencer best fits your intended needs.

    The adjustable gas block on the ROMEO may have raised muzzle dB numbers for the SureFire SOCOM RC2 and lowered at ear . Over 140dB seems high for an 18” barrel. But the adjustable gas block may show that there was less blowback when using the OSS HELIX since I had to open it up to get the Dynamic Defense ROMEO upper to cycle.

    The HELIX HX-QD showed some impressive at-ear numbers, no doubt related to its flow-through technology. The left hand threaded mounting system locks on tight and stays put. And the build quality appears to be solid and consistent.

    Next week we will finish up the OSS HELIX HX-QD 556 with a few other hosts and hopefully have our own CSASS rifle for the HX-QD 762 testing.


     


    Published on August 4, 2018 – TFBTV

    In this episode of TFBTV, Ivan (from Kit Badger) runs down the SureFire SOCOM 300 SPS Suppressor. Arguably SureFire’s quietest 30 Caliber Suppressor. While designed around the 300 Blackout Cartridge, and full auto rated down to a 5.5″ barrel, it can serve on various weapon platforms. Whether it is 5.5″ Sig Rattler or a 20″ 300 Win Mag bolt gun, this suppressor will preform. Check out some of the nuances with this 300 SPS suppressor versus the SureFire SOCOM 762 RC2.

    Published on Aug 4, 2018 – Suppressed Nation
    The Rugged Razor 762 is a suppressor I have been fascinated with since the first time I seen it. From its 6.4″, 15.3oz , 1.5″ diameter SS construction to its changeable caliber specific end caps and dual taper lock mounting system. Its built to last and backed by a company that has your back just incase of an accident. All metering was done by Hansohn Brothers with a B&K 2209 that meets milspec that’s been professionally calibrated to insure accurate numbers. All metering was done with the meter at the correct height and distance according to milspec standards.

    Special thanks: MAC Tactical 

    Pete

    Editor In Chief- TFB
    LE – Silencers – Science
    [email protected]


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