SSS.6.151- Surefire SOCOM556-RC3 and the MK18 5.56x45mm Short Barrel Automatic AR15 Rifle (Free Version)

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Surefire SOCOM556-RC3 on the MK18 5.56x45mm AR15 with 10.3-in Barrel

The SOCOM556-RC3 is manufactured by Surefire. It is a 223 caliber centerfire rifle silencer, intended to suppress the 5.56x45mm NATO cartridge from barrels greater than or equal to 10 inches in length. It has a 1.5-inch diameter and is 6.3 inches long. The silencer mounts to the host firearm with a proprietary mounting system; the user may choose from various Surefire flash hider and muzzle brake mounts. The outer tube is constructed of heat treated stainless steel. The baffles are constructed of Inconel steel alloy.  Portions of the silencer, including the proximal blast chamber and distal end, are 3D printed. The silencer body with mount collar weighs 16.9 ounces and the 3-prong flash hider weighs 3.9 ounces, for a total system weight of 20.8 ounces, as tested. The SOCOM556-RC3 can be obtained from Silencer Shop.

This review contains results from two separate tests. PEW Science tested the SOCOM556-RC3 on the MK18 with the SOCOM 3-Prong flash hider mount and also with the WARCOMP closed-tine flash hider mount. The SOCOM 3-Prong flash hider mount is non-ported and contains so-called “labyrinth seals.” The presence of the seal rings, and more importantly the lack of ports, results in the 3-prong flash hider system exhibiting significantly different gas dynamics than does a ported WARCOMP-equipped Surefire SOCOM556 silencer system.  This phenomenon, and its influence on increased hazards to both system operators and bystanders, was investigated in the following analytical test report white papers:

Note that the SOCOM556-RC3 also exhibits different gas dynamics due to the above phenomenon.  Additionally, the silencer exhibits varying gas dynamics between the use of closed-tine muzzle devices and open-tine systems, independent of mount seals and porting.  The testing and analysis presented herein examines these behaviors.

High Level Summary:

1. The gas dynamics of the RC3 are extremely sensitive to mount geometry in the blast chamber. Closed-tine muzzle devices may exacerbate first-round signatures (sound and flash). However, the first-round signature from the RC3 may be relatively severe, regardless of mount type.

2. The overall signature of an RC3-equipped MK18 system is largely muzzle blast driven. WARCOMP mount blast load leaks may be masked to personnel other than the operator, resulting in erroneous determinations of hazard reduction without appropriate evaluation.

3. The high flow rate (low back pressure) of the RC3, although it may pay dividends in “gas blow back” hazard reduction, nullifies the benefit of ejection port blast reduction to the operator due to high amplitude muzzle signature throughout the shot string and subsequent blast wave coalescence.  This occurs in the free field and is likely even more severe near reflecting surfaces.

Cautions:

  • The WARCOMP mount increases postulated operator hazards in all tested regimes.  Personal protective equipment (PPE), including eye and ear protection, is recommended for the operation of suppressed small arms, in general.

  • This is a 10.3-in barrel MK18 dataset; 14.5-in barrel M4A1 testing and analysis results are forthcoming.  Performance is a function of holistic suppressed weapon system characteristics (the silencer in combination with the weapon). Extrapolation of testing and analytical results to and from each weapon system may produce erroneous and potentially unconservative conclusions. Personnel hazards do not scale directly nor linearly between the two host weapon systems.

Both sets of test results in this Sound Signature Review are of the SOCOM556-RC3 on the MK18 Automatic AR15 rifle rifle, chambered in 5.56x45mm NATO with a 10.3-inch barrel. Federal XM193 55gr ammunition was used in the tests. The standard PEW Science MK18 test host weapon system is described in Public Research Supplement 6.51.

  • Section 6.151.1 contains SOCOM556-RC3 test results and analysis using the SOCOM 3-Prong flash hider mount.

  • Section 6.151.2 contains test results and analysis using the WARCOMP closed-tine flash hider mount.

  • Section 6.151.3 contains a detailed comparison Case Study of the sound signatures and gas dynamics from the SOCOM556-RC3 silencer on the MK18 with both of the mount systems (Members Only).

  • Section 6.151.4 contains overall Suppression Rating comparisons of the SOCOM556-RC3 with with dedicated 223 and 30 caliber silencers on the current market, including the Otter Creek Labs Polonium-30, AAC M4-2000 Mod 08, PTR VENT 3, SilencerCo Velos LBP, BOSS Guillotine, CAT WB, PWS BDE 556, CAT ODB, Aero Precision Lahar-30L, Lahar-30, HUXWRX FLOW 762 Ti, Maxim Defense DSX, Thunder Beast Dominus, KAC 5.56 QDC, CGS SCI-SIX, Dead Air Nomad-30, YHM Turbo T2, Dead Air Sandman-S, HUXWRX FLOW 556k, Energetic Armament ARX, KAC QDSS-NT4, Rugged Razor556, Otter Creek Labs Polonium and Polonium-K, Surefire SOCOM556-RC2, HUXWRX HX-QD 556 and HX-QD 556k, Q Trash Panda, CGS Helios QD, SilencerCo Saker 556, Rugged Razor762, and others.

  • Section 6.151.5 contains an article summary and PEW Science laboratory staff opinions.

Summary: When paired with the 10.3-in barrel MK18 and fired with Federal XM193, the Surefire SOCOM556-RC3 mounted with the SOCOM 3-Prong flash hider achieved a composite Suppression Rating™ of 28.8 in PEW Science testing. When mounted with the WARCOMP flash hider on the same host weapon and fired with the same ammunition, the SOCOM556-RC3 achieved a composite Suppression Rating of 26.5.

As with all weapon systems, the user is encouraged to examine both muzzle and ear Suppression Ratings.

Relative Suppression Rating Performance is Summarized in SSS.7 - PEW Science Rankings

6.151.1 SOCOM556-RC3 Sound Signature Test Results (SOCOM 3-Prong Flash Hider)

A summary of the principal Silencer Sound Standard performance metrics of the Surefire SOCOM556-RC3 with the 3-Prong Flash Hider is shown in Table 1. The data acquired 1.0 m (39.4 in) left of the muzzle is available for viewing to all. The data acquired 0.15 m (6 in) right of the shooter’s ear is only available to membership supporters of PEW Science and the Silencer Sound Standard. You can support public PEW Science testing, research, and development with a membership, here. State-of-the-art public firearm sound signature testing and research conducted by PEW Science is supported by readers like you.

 

Table 1. Surefire SOCOM556-RC3 (3-Prong FH) Sound Metric Summary

 

6.151.1.1 SOUND SIGNATURES AT THE MUZZLE

Real sound pressure histories from a 6-shot test acquired with PEW-SOFT™ are shown below. Six cartridges were loaded into the magazine, the fire control group positioned to single-shot, and the weapon was fired until the magazine was empty and the bolt locked back on the follower of the empty magazine. Only five shots are considered in the analysis. The signatures of Shot 6 are displayed in the data presentation but are not included in the analysis to maintain consistency with the overall PEW Science public dataset and bolt-closing signatures. The waveforms are not averaged, decimated, or filtered. The data acquisition rate used in all PEW Science laboratory sound signature testing is 1.0 MS/s (1 MHz). The peaks, shape, and time phasing (when the peaks occur in relation to absolute time and to each other) of these raw waveforms are the most accurate of any firearm silencer testing publicly available. PEW-SOFT data is acquired by PEW Science independent laboratory testing; the recognized industry leader in silencer sound research. For more information, please consult the Silencer Sound Standard.

The primary sound signature pressure histories for all 6 shots with the SOCOM556-RC3 with the 3-Prong Flash Hider are shown in Figure 1a. The sound signatures of Shot 1 and Shot 2 are shown in Figure 1b, in early time. The real sound impulse (momentum transfer potential) histories from the same 6-shot test are shown in Figure 2a. In Figure 2b, a shorter timescale is shown comparing the impulse of Shot 1 to that of Shots 2, 3, and 5.

Fig 1a. Surefire SOCOM556-RC3 (3-Prong FH) 5.56x45mm NATO MK18 Automatic Rifle Muzzle Sound Pressure Signature

Fig 1b. Surefire SOCOM556-RC3 (3-Prong FH) 5.56x45mm NATO MK18 Automatic Rifle Sound Pressure Signature

Figure 2a. Surefire SOCOM556-RC3 (3-Prong FH) 5.56x45mm NATO MK18 Automatic Rifle Muzzle Sound Impulse Signature

Figure 2b. Surefire SOCOM556-RC3 (3-Prong FH) 5.56x45mm NATO MK18 Automatic Rifle Muzzle Sound Impulse Signature

There are significant differences in combustion propagation, muzzle blast impulse accumulation, and overall gas dynamics measured from the Surefire SOCOM556-RC3 than were measured from the SOCOM556-RC2 on the same weapon system (6.52).  The silencers possess similar sized external envelopes and use the same mount systems, but internal and distal venting schemes in the RC3 result in the following notable measured performance differentials:

  1. The SOCOM556-RC3 produces significantly higher amplitude muzzle blast than the RC2, and does so with expedient early-time jetting that possesses a longer initial positive phase duration (Fig. 1b).

  2. The blowdown of the RC3 system is significantly faster than the RC2 (Fig. 1a, 35 ms, prior to ground reflection). This is a direct result of the RC3’s higher flow rate (lower back pressure).

  3. Bolt-carrier group return to battery is also delayed (Fig. 1a), for the same reason in (2).

  4. Both the higher muzzle blast amplitude and rate of blast load accumulation from the SOCOM556-RC3 produce more intense and longer duration blast load impulse than the RC2 (Fig. 2a).

  5. First-round-pop (FRP) from the RC3 produces a significant differential in gas dynamics with respect to subsequent shots (Fig. 2b). Severe jetting is noted during FRP after typical peak accumulation, in later time. This behavior is in stark contrast to that of the SOCOM556-RC2 on the same weapon system, which displays blast impulse accumulation that normalizes relatively expediently post-peak (Fig. 2b, 6.52.1.1).

In totality, the above performance differentials result from the type of “low back pressure” design employed in the Surefire SOCOM556-RC3.  The so-called Total Signature Reduction Technology present in the RC2 series has been modified by Surefire in the RC3 implementation.

PEW Science Research Note 1:  In previous generations of Surefire silencers, combustion gasses expanding into the blast chamber from the muzzle orifice are vented into an annular cavity through proximal blast chamber port arrays.  As stagnation of the under-expanded gas propagation is somewhat delayed in time due to that venting mechanism, the RC2 series, for example, exhibits lower overall back pressure than traditional silencer designs.  The reduction of additive blast chamber impulse, resulting in a somewhat lower alpha parameter, coupled with limited baffle porting to control the external rate of gas momentum accumulation (Omega, 6.40), defines the holistic signature characteristics of the RC2 silencer design pedigree.  In the RC3 series, a similar design is employed.  However, instead of delaying pressure stagnation within a finite time window, the annular vent paths of the RC3, fed by both the blast chamber and baffle vents, are directly and expediently vented to atmosphere though distal ports circumferential to the primary bore end cap orifice. This distal vent array is the final stage of a secondary passive attenuator; a similar component present in silencers from CGS Group, SIG, SilencerCo, and others.  It is considerably less advanced than others, such as those from HUXWRX or stages of certain technologies from Combat Application Technologies (CAT).  For a discussion of various back pressure-reducing designs present in silencers with high early time or late time flow rates (or both), see PEW Science Member Research Supplement 6.124.  This supplement provides an overview summary of Flow-Through, Total Signature Reduction, SURGE BYPASS, and Forward Flux technologies.

PEW Science Research Note 2: The performance of a passive blast attenuator is a function of various parameters.  In a rifle silencer, traditional attenuator designs must be modified to address early-time shock reflections that develop in close proximity to the muzzle orifice if they are to possess secondary high flow stages with holistic back pressure reducing benefits.  The design must minimize early time impulse accumulation near the orifice (alpha), while managing transition to the the secondary stage consistently (Omega control).  In the Surefire SOCOM556-RC3, this is somewhat accomplished through angle of incidence on the concave face of the blast baffle and tuned with aft vent array location.  After the first gas expansion stage is complete, the RC3 reverts to a passive vent mechanism that is similar to that implemented in vented CGS Hyperion technology, with which it shares some design similarities.  The RC3 baffle flow is transmitted to the annulus at multiple porting stages.  The annulus is directly vented to atmosphere at the distal end, at which both the annular venting and primary nozzle geometries are tuned to manage shock propagation and flash reduction.  The practical consequence of the RC3 vent design, and its second stage, is two-fold:

  1. The design may possess extreme sensitivity to initial conditions (blast chamber muzzle orifice jet input dynamics).

  2. If (1) is not properly tuned, unintended consequences may result, to include uncontrolled distal flow rate.

The two consequences above are of importance to the end-user, as (1) may dictate muzzle device preference and (2) may significantly influence both sound and flash suppression.  These consequences occur despite distal orifice geometry intended to shape exit jet dynamics.

PEW Science Research Note 3: The consequences outlined in Research Note 2 above are directly visible in the measured FRP muzzle blast impulse propagation history displayed in Figure 2. The FRP signature from the Surefire SOCOM556-RC3 may be unpredictable and inconsistent. This may result in both increased blast hazard, as well as flash signature during the first shot fired from a short-barrel rifle like the standard MK18.  This phenomenon is also expressed with a mount change; the closed-tine WARCOMP mount used in the second test outlined in this report also produces erratic blast load propagation during FRP.  This is independent of the WARCOMP mount leak that has been significantly studied in PEW Science laboratory research.  WARCOMP mount test results are examined in Section 6.151.2 of this report.  A detailed comparison of blast and shock dynamics between the two systems is provided to PEW Science Members in Section 6.151.3.  The SOCOM556-RC3 first-round signature may present as erratic on user platforms, regardless of mount system.  In all cases tested, postulated hearing damage risk potential to bystanders during FRP is over twice as severe as follow-up shots, on average, with the RC3 silencer on the MK18.  First-round flash signature is most likely also exacerbated, especially when compared to that of the previous generation RC2 on the same weapon system.

After FRP, the RC3 signature significantly normalizes.  However, later in the shot string, eventual gas momentum divergence occurs (Shot 5, Fig. 2b).  This is driven by system heating, despite the high flow gross flow rate of the system.  This divergence continues and was also measured in the subsequent WARCOMP mount test, again beginning with Shot 5.  This further supports the conclusion of a heat-driven phenomenon in which less gas expansion is facilitated prior to distal vent.  In a high round-count continuous fire evaluation, it is likely that the accumulation normalizes at some level at or below that of maximum FRP.

PEW Science Research Note 4:  One of the positive attributes of the RC3 design is the likelihood of users experiencing less “gas blow back” from the MK18 weapon breach during operation, when compared to that of the previous generation RC2.  This benefit is the direct result of the lower back pressure of the RC3, as previously discussed.  This higher flow rate also reduces the severity of ejection port blast loads to which the operator is subjected.  Nonetheless, the muzzle blast propagation from the SOCOM556-RC3 is severe enough such that some of the benefits of its reduced back pressure are negated.  The wave coalescence from muzzle and ejection port blast results in similar operator hazard when using the RC3 as is present with an RC2 on the same MK18 weapon system, in the free field.  In-depth examination of the signatures measured at the operator’s head with the 3-Prong mount is presented in Section 6.151.1.2 of this report for PEW Science Members.  WARCOMP mount operator hazard analysis is presented in Section 6.151.2.2.  These hazards are also reflected in the detailed PEW Science Suppression Ratings at the beginning of this report.

PEW Science Research Note 5: As in all semiautomatic AR15 weapon testing, a second pressure pulse originates from the ejection-port signature of the weapon and it occurs early enough in time such that its waves coalesce with that of the muzzle signature. However, in late time (at approximately 87 ms in Figure 1a) the mechanical noise of the bolt closing is observed. The pressure signature of Shot 6 does not display this event due to the bolt remaining open after the sixth and final round is fired from the magazine.

PEW Science Research Note 6: The closing time of the AR15 bolt is directly related to the flow restriction of a silencer for a given weapon system. PEW Science has determined bolt closing time variation from the unsuppressed state to be a reliable indicator of silencer back pressure, with strong correlation with the PEW Science Back Pressure Metric, Omega and the alpha parameter. However, PEW Science has also determined that the indicator is unreliable upon upper receiver fouling. Sound signatures are not influenced by this fouling, as these kinematics occur in late time, after gas venting to atmosphere. Momentum transfer, weapon condition (upper receiver fouling), and other factors, can significantly influence bolt closing time. PEW Science urges the reader to exercise extreme caution if using the published bolt closing time to make determinations regarding silencer flow restriction (back pressure) or weapon system kinematics. This type of calculation may provide erroneous results, as the weapon condition at the time of each test is not published data. The time-scale duration showing bolt closing time is only published by PEW Science such that the signature data pedigree may be verified.

The shape, timing, and magnitudes of the early-time pressure pulses and overall shape of the impulse waveforms measured at the muzzle, from shot-to-shot, are relatively consistent. The consistency of the waveform amplitudes highlight the silencer’s overall sound performance consistency at the muzzle after the FRP, as well as the relative consistency of the tested automatic rifle firearm configuration.

As typically indicated, first-round sound signatures always differ from subsequent shots, as the atmosphere within the silencer changes. The FRP phenomenon cannot always be shown by viewing only the peak sound pressure. This is one of the reasons why The Silencer Sound Standard requires examining multiple sound signature metrics. Ammunition consistency can play a role in the determination of FRP, however, the close examination of measured pressure and impulse waveforms typically excludes ammunition from the possible factors influencing true FRP, due to the relative consistency of most high quality factory ammunition.

PEW Science Research Note 7: Note that the muzzle Suppression Rating of the SOCOM556-RC3 with the 3-Prong mount is 27.2 and the at-ear Suppression Rating is 22.4; the same zone on the Suppression Rating Dose Chart. The lower back pressure of the SOCOM556-RC3 compared with the SOCOM556-RC2 contributes to a less severe ejection port blast signature.  However, the more severe muzzle blast from the RC3 nullifies the reduction in ejection port blast hazard to the shooter on the standard MK18 weapon system. The WARCOMP mount may further increase this shooter hazard, as examined in Section 6.151.2.

The signatures measured at the shooter’s ear with the 3-Prong mount are presented in the PEW Science Member version of this report.  WARCOMP closed-tine flash hider mount muzzle test data and analysis is presented below.

6.151.2 SOCOM556-RC3 Sound Signature Test Results (WARCOMP Flash Hider)

A summary of the principal Silencer Sound Standard performance metrics of the SOCOM556-RC3 with the WARCOMP Closed-Tine Flash Hider is shown in Table 2. The data acquired 1.0 m (39.4 in) left of the muzzle is available for viewing to all. As stated in Section 6.151.1, the data acquired 0.15 m (6 in) right of the shooter’s ear is only available to membership supporters of PEW Science and the Silencer Sound Standard. You can support PEW Science testing, research, and development with a membership, here. State-of-the-art firearm sound signature testing and research conducted by PEW Science is supported by readers like you.

 

Table 2. Surefire SOCOM556-RC3 (WARCOMP) Sound Metric Summary

 

6.151.2.1 SOUND SIGNATURES AT THE MUZZLE

Real sound pressure histories from a 6-shot test acquired with PEW-SOFT™ are shown below. The waveforms are not averaged, decimated, or filtered. The data acquisition rate used in all PEW Science testing is 1.0 MS/s (1 MHz). The peaks, shape, and time phasing (when the peaks occur in relation to absolute time and to each other) of these raw waveforms are the most accurate of any firearm silencer testing publicly available. PEW-SOFT data is acquired by PEW Science independent testing; the industry leader in silencer sound research. For more information, please consult the Silencer Sound Standard.

The primary sound signature pressure histories for all 6 shots with the SOCOM556-RC3 with the WARCOMP Closed-Tine Flash Hider are shown in Figure 5a. The sound signatures of Shot 1 and Shot 2 are shown in a smaller time window in Figure 5b. The real sound impulse (momentum transfer potential) histories from the same 6-shot test are shown in Figure 6a. In Figure 6b, a shorter timescale is shown comparing the impulse of Shot 1 to that of Shot 2, Shot 3, and Shot 4.

Fig 5a. Surefire SOCOM556-RC3 (WARCOMP) 5.56x45mm NATO MK18 Automatic Rifle Muzzle Sound Pressure Signature

Fig 5b. Surefire SOCOM556-RC3 (WARCOMP) 5.56x45mm NATO MK18 Automatic Rifle Muzzle Sound Pressure Signature, Short Time Window

Fig 6a. Surefire SOCOM556-RC3 (WARCOMP) 5.56x45mm NATO MK18 Automatic Rifle Muzzle Sound Impulse Signature

Fig 6b. Surefire SOCOM556-RC3 (WARCOMP) 5.56x45mm NATO MK18 Automatic Rifle Muzzle Sound Impulse Signature, Short Time Window

Just as was noted in PEW Science testing of the SOCOM762-RC2 on a 20-in barrel .308 bolt-action rifle with the WARCOMP mount (6.26), the testing of the SOCOM556-RC2 on a 10.3-in barrel 5.56mm MK18 and M4A1 with the WARCOMP mount (6.52 and 6.128), and the testing of the SOCOM556-MINI2 on the M4A1 with the WARCOMP mount (6.144), the MK18 testing of the Surefire SOCOM556-RC3 with the WARCOMP mount displays more severe gas momentum accumulation due to a leak out of the mount-collar interface, than it does with the 3-Prong flash hider.  This is visible in pressure space (Figure 5) and somewhat visible in impulse space (Figure 6).  

Despite the occurrence of a similar blast load leak phenomenon originating from the WARCOMP mount ports and lack of mount interface seal, the behavior of the RC3 with the WARCOMP is somewhat different than the behavior of silencers in the previous RC2 generation.  The following performance factors  highlight this difference:

  1. The severe blast load impulse accumulation with the WARCOMP mount (Figure 6) is only present during the first shot (FRP).

  2. The RC3 produces extremely similar post-FRP blast load impulse accumulation with the WARCOMP to that produced with the 3-Prong mount (ref. Fig. 2 and Fig. 6, along with Member Case Study Fig. 10 in Section 6.151.3).

PEW Science Research Note 10:  The RC3 produces free field muzzle blast signatures with the WARCOMP that are different from those produced by the RC2 series with a WARCOMP because the RC3 flow field is extremely sensitive to blast chamber geometry (as discussed in Research Note 2).  The WARCOMP mount tested is a closed-tine model, which produces different blast load reflection timing in the first chamber. PEW Science testing indicates this mount sensitivity is confined to the first shot, on the MK18 weapon system, with the mount type tested. This severely erratic blast load accumulation may lead observers to believe it is due to a WARCOMP mount leak. On the contrary, while the WARCOMP blast load leak does contribute to additional free field blast hazard, the distal venting of the RC3 is so severe that the mount leak coalescence is almost masked by muzzle blast.

It is not until the blast hazard to the weapon operator is examined that the more significantly increased hazard from the WARCOMP mount blast load leak is demonstrated. This increased operator hazard phenomena is the same as was observed in previous generation RC2 WARCOMP testing and analysis.  See Member Section 6.151.2.2.

PEW Science Research Note 11: The Surefire SOCOM silencer mount interface possesses a taper that does not enact a complete gas seal. Machined circumferential recesses on some mounts (the so-called “labrynth seals”) create turbulence that disrupt gas flow and may reduce the rate of high pressure gas propagation to atmosphere at the mount interface. The WARCOMP family of mounts, regardless of the presence of these machined recesses, possess drilled ports that direct thrust forces in the unsuppressed state to counteract unfavorable recoil forces.  When suppressed, the WARCOMP mount ports direct a significant amount of high pressure gas flow to the mount interface and the lack of adequate seal in the SOCOM silencer mount system results in significant blast load propagation to atmosphere.  The blast load from the mount leak propagates in addition to the blast load originating from the end cap of the silencer.  The two loads are superimposed at approximately 29.7 ms in Figure 5b.  The relatively fast rise-times of these blast loads are indicative of shocks, further indicating a sudden release of high pressure gas to atmosphere, and is consistent with all Surefire suppressed WARCOMP mount silencer test results conducted by the PEW Science laboratory, to date.  The difference with the SOCOM556-RC3, compared with the RC2, is that the end cap of the silencer is also producing severe shock loads.  As stated in Research Note 10, this may lead the observer to mistake severe free field signature for a mount leak, when in fact, it is simply typical RC3 first round suppression performance.  This may also lead observers to mistakenly believe that the WARCOMP mount does not influence performance.  This erroneous conclusion is addressed in the operator hazard examination in Section 6.151.2.2 and displayed in the shooter’s ear Suppression Rating differential at the beginning of this report.

More detailed comparisons between 3-Prong Flash Hider mount and WARCOMP Closed-Tine Flash Hider mount performance with the Surefire RC3 on the MK18 weapon system are provided in a Member Case Study in Section 6.151.3.

The signatures measured at the shooter’s ear with the WARCOMP are presented in the PEW Science Member version of this report, along with an in-depth case study comparing the gas dynamics of the 3-Prong and WARCOMP with the RC3 system on the MK18.

Gross Suppression Rating comparisons of silencers tested on the MK18 in the public research pedigree are provided below.

6.151.4 Suppression Rating Comparison (5.56x45mm from the MK18)

Figure 13 presents a comparison of the PEW Science Suppression Rating of the Surefire SOCOM556-RC3 with both the 3-Prong Flash Hider and WARCOMP Closed-Tine Flash Hider mounts with that of several other silencers on the MK18 weapon system. The standard PEW Science MK18 test host weapon system is described in Public Research Supplement 6.51.

Figure 13. Suppression Rating Comparisons of the Surefire SOCOM556-MIN2 and SOCOM556-RC2 with different mounts and the CAT WB, Using PEW-SOFT 5.56x45mm Supersonic Test Data and PEW Science Analysis

Figure 13 presents an overall summary of the postulated hazards to the operator and bystanders when fielding a variety of different silencers on the standard MK18 weapon system.  The Surefire SOCOM556-RC3 is shown with two different muzzle devices.  Hazards are expressed with the Suppression Rating; a holistic parameter that captures human inner ear damage risk potential from a measured impulsive complex overpressure signature during the entire time regime of weapon operation, including combustion, complete blowdown, and all mechanical operation, including the carrier group returning to battery, in the true free field. The parameter may be used with the dose chart at the beginning of this report.  The PEW Science Suppression Rating is a damage risk criterion (DRC), a lower Suppression Rating indicates a higher personnel hazard in the free field - it is not a subjective quantity; it is an objective quantification of hearing damage risk potential.

The following gross conclusions can be made from the above:

  1. The Surefire SOCOM556-RC3 with the 3-prong flash hider produces a more severe free field hazard than the RC2 with the same mount on the same weapon system.  The hazard to the weapon system operator is slightly reduced with the RC3 over the RC2, but the differential is minimized due to the severe distal vent jetting from the RC3 and the subsequent blast wave coalescence at the operator’s head.

  2. The WARCOMP mount with the RC3 increases blast hazard to the shooter and bystanders when compared to use of the 3-Prong mount on the MK18, just as occurs in all Surefire rifle silencer configurations. However, WARCOMP blast hazard differentials in the free field are somewhat masked by the RC3, due to the RC3’s severe muzzle blast. The operator is still subjected to increased blast hazard risk with the WARCOMP mount while using the RC3, though the holistic shooter hazard is somewhat reduced over that of the RC2 with the WARCOMP mount due to reduced ejection port blast wave coalescence brought about by the RC3’s higher gross flow rate (lower back pressure).

  3. The free field hazard reduction with a 3-Prong mounted Surefire SOCOM556-RC3 is similar to that of a Q Trash Panda (6.61), HUXWRX HX-QD 556 (6.54), KAC QDSS-NT4 (6.78), or Aero Precision Lahar-30 (6.116), on the standard MK18 weapon system.

  4. The shooter’s ear hazard reduction with a 3-Prong mounted Surefire SOCOM556-RC3 is similar to that of a 3-Prong mounted SOCOM556-RC2 (6.52), CGS Helios QD (6.66), HUXWRX HX-QD 556k (6.64), KAC 5.56 QDC (6.104), or Liberty Precision Machine Torch (6.126), etc.  Despite the RC3’s high flow rate that reduces ejection port blast hazard, its muzzle blast is severe enough such that the level of protection to the weapon operator is reduced.

  5. When used with a closed-tine WARCOMP mount, the Surefire RC3 provides a shooter’s ear hazard reduction similar to that of other WARCOMP-mounted Surefire silencers (elevated operator risk, compared to most systems on the MK18).

As previously detailed in this report, there are other nuanced performance factors of the RC3 system that may be significant to end users, and are not immediately apparent by examining the chart in Figure 13.  These factors include:

  1. The gas dynamics of the RC3 are extremely sensitive to mount geometry in the blast chamber. Closed-tine muzzle devices may exacerbate first-round signatures (sound and flash). However, the first-round signature from the RC3 may be relatively severe, regardless of mount type.

  2. The overall signature of an RC3-equipped MK18 system is largely muzzle blast driven. WARCOMP mount blast load leaks may be masked to personnel other than the operator, resulting in erroneous determinations of hazard reduction without appropriate evaluation.

  3. The high flow rate (low back pressure) of the RC3, although it may pay dividends in “gas blow back” hazard reduction, nullifies the benefit of ejection port blast reduction to the operator due to high amplitude muzzle signature throughout the shot string and subsequent blast wave coalescence.  This occurs in the free field and is likely even more severe near reflecting surfaces.

PEW Science Research Note 17: The Surefire Total Signature Reduction technology modification present in the RC3, while purposely implemented to reduce back pressure, is shown in this test report to produce less competitive performance than several competing designs. Of the high flow rate designs on the current market, including so-called hybrid designs in which high early time flow rate is throttled to control later time gas momentum propagation, this latest implementation of the Surefire technology provides lower overall performance than that implemented in the previous generation RC2 series.  When compared to more advanced technologies (CAT SURGE BYPASS, HUXWRX Flow-Through, and PTR PIP, for example), the RC3 technology is significantly outperformed in several metrics and gross blast and shock dynamics.

As detailed in this report, the Suppression Rating at the shooter’s ear may be significantly influenced by the ejection port signature from an AR15; all other things equal. For details on performance increases that are possible when “tuning” an AR-15 weapon system for a silencer, please see Review 6.111. It is important to note that not all silencers will possess a significant increase in shooter’s ear Suppression Rating from weapon tuning. Signature at the operator’s head is a function of both muzzle and ejection port signatures from the AR-15 weapon system. Specific weapon system parameters will dictate modification efficacy.  The evaluations of the Surefire SOCOM556-RC3 detailed in this report exemplify the limits of modifying a legacy technology to achieve more advanced flow dynamics.  Uncontrolled distal flow rate significantly influences weapon operator hazard reduction efficacy.

Small arm weapon system suppression performance is a spectrum. The PEW Science Suppression Rating and the Silencer Sound Standard help quantify this spectrum for end users and industry, objectively.

6.151.5 Review Summary: Surefire SOCOM556-RC3 on the MK18 5.56x45mm AR15 with 10.3-in Barrel

When paired with the 10.3-in barrel MK18 and fired with Federal XM193, the Surefire SOCOM556-RC3 mounted with the SOCOM 3-Prong flash hider achieved a composite Suppression Rating™ of 28.8 in PEW Science testing. When mounted with the WARCOMP flash hider on the same host weapon and fired with the same ammunition, the SOCOM556-RC3 achieved a composite Suppression Rating of 26.5.

As with all weapon systems, the user is encouraged to examine both muzzle and ear Suppression Ratings.

PEW Science Laboratory Staff Opinion:

The Surefire SOCOM556-RC3 is a full-size 5.56mm rifle silencer that interfaces with existing Surefire SOCOM muzzle devices and possesses reduced back pressure compared to some designs. Users should note that the gross suppression performance of the RC3 series is significantly different than that of the previous generation RC2.  Operator hazards in the free field may be similar with both generations, on certain weapon systems.

Two mounts (the SOCOM 3-Prong Flash Hider and closed-tine WARCOMP flash hider) were used in the testing of the SOCOM556-RC3 silencer on the MK18 rifle. Previously, PEW Science tested a variety of Surefire silencers on multiple weapon systems and cartridges with both mounts. Testing and analysis results indicate that the use of the WARCOMP is unfavorable for hazard reduction when compared with the 3-Prong Flash Hider mount, regardless of cartridge, barrel length, and silencer.  In this evaluation of the RC3, it was concluded that hazard reduction to the weapon operator is more significantly influenced by WARCOMP mount use than is the general free field hazard reduction to bystanders.

The Surefire SOCOM556-RC3 possesses “balanced” performance attributes, in a gross sense.  However, there are two significant differences between RC3 performance at the operator’s location when compared to that of several silencers.  The RC3 has significantly more intense muzzle blast than some legacy silencers and some more advanced modern silencers. This increases operator hazard, particularly outside the free field (indoors, near barriers, etc).  The RC3’s FRP signature is potentially erratic (as measured in both tests presented in this report, with two different mounts).  This pushes blast load positive phase impulse accumulation further to late-time; a phenomenon typically only seen in high back pressure systems.  Although the RC3 is “low back pressure,” the hazard to the operator may be similar to firing a high back pressure silencer on the same weapon system, during the first shot.

The RC3 does subject shooters to less “gas blow back” than the previous generation RC2 design. This performance attribute may be attractive to some users. However, there exist other high performance silencers with balanced design attributes that control late-time gas momentum propagation in a superior fashion, like the CAT WB or PTR VENT 3. As it stands, in the current PEW Science research pedigree, the holistic suppression performance of the RC3 is lower than that of several other designs on the standard MK18, including those with high flow rate. Such designs include the HUXWRX FLOW 762 Ti, CAT ODB and WB, SilencerCo Velos, Liberty Precision Machine Torch, PTR VENT 3, and others.

The practical consequences of the RC3 design are that the silencer may possess extreme sensitivity to initial conditions (blast chamber muzzle orifice jet input dynamics).  If  mount geometry is not properly tuned, unintended consequences may result, to include uncontrolled distal flow rate.  This is of importance to the end-user, as it may dictate muzzle device preference as it significantly influences both sound and flash suppression.  These consequences occur despite distal orifice geometry intended to shape exit jet dynamics.  Regardless, first-round MK18 suppression performance of the RC3 system is shown in this report to be eclipsed by that of the previous generation RC2 series, by a significant margin.

In this review, the Surefire SOCOM556-RC3 performance metrics depend upon suppressing a supersonic centerfire rifle cartridge on a short barrel gas-operated rifle, which is an incredibly difficult task. PEW Science encourages the reader to remain vigilant with regard to all supersonic centerfire rifle suppression claims. The gas volume and combustion products created by the firing of the supersonic 5.56x45mm cartridge are significant; the measured pressure and impulse magnitudes, and their durations, illustrate this fact. Silencer performance on automatic (reciprocating) rifles depends on many factors. Weapon configuration may significantly influence total suppressed small arm system performance.

The hearing damage potential of supersonic centerfire rifle use is significant. PEW Science encourages the reader to consider the Suppression Rating when deciding on an appropriate silencer and host weapon combination for their desired use.