SSS.6.90 - Resilient Suppressors RS9 and the Heckler and Koch SP5 9x19mm Subgun
/Resilient Suppressors RS9 on the HK SP5 9x19mm Subgun with 8.9-in barrel
The RS9 is designed and manufactured by Resilient Suppressors. It is a 9mm centerfire submachinegun silencer, intended to suppress the 9x19mm NATO cartridge from barrels of any length. It may also be used with subsonic 300 BLK and other cartridges. The RS9 has a 1.37-inch primary distal diameter with a 1.7-inch proximal diameter. It is 6.75 inches long. The silencer may be attached to the host weapon with a variety of mount systems that use the so-called “HUB” mount threading of 1.375” x 24tpi. The RS9 includes a dedicated (and specialized) direct thread mount, which increases the total length of the silencer to 7 inches. The entirety of the RS9’s baffle stack is 17-4 heat treated stainless steel. The silencer is user-serviceable and weighs 10.1 ounces. With the specialized direct thread mount, the silencer weighs 12.4 ounces, as tested. The RS9 can be obtained from Resilient Suppressor Dealers.
PEW Science is an independent private testing laboratory and also the world’s only publicly funded suppressed small arms research cooperative. Testing, data analysis, and reporting is generated with funding provided by PEW Science members. Any test data that is generated with any portion of private funding contains this disclosure. The testing and data production for this Sound Signature Review was funded in part by PEW Science Project PEW-RS-031-001-22. Therefore, data pertaining to the RS9 in this Sound Signature Review is published with the express written permission of Resilient Suppressors, LLC.
This Sound Signature Review contains single-test results using the Resilient Suppressors RS9 with the direct thread mount on the semiautomatic Hecker and Koch SP5 subgun, chambered in 9x19mm NATO with a 8.9-inch barrel. Speer Lawman 147gr ammunition was used in the test, in which its velocity was subsonic. The standard PEW Science HK SP5-A2 test host weapon system is described in Public Research Supplement 6.85.
Section 6.90.1 contains the RS9 test results and analysis.
Section 6.90.2 contains Suppression Rating comparisons of the RS9 with the GSL Phoenix fired on the Heckler and Koch SP5-A2 and with the RS9 fired on the Heckler and Koch SP5K-PDW (as detailed in SSS.6.91).
Section 6.90.3 contains the review summary and PEW Science subjective opinions.
Summary: When paired with the 8.9-in barrel HK SP5-A2 with 80-deg locking piece and fired with Speer Lawman 147gr, the Resilient Suppressors RS9 mounted with the direct thread mount achieved a composite Suppression Rating™ of 53.1 in PEW Science testing. As with all weapon systems, the user is encouraged to examine both muzzle and ear Suppression Ratings.
The 5.8-in barrel HK SP5K-PDW performance of the RS9 is detailed in Sound Signature Review 6.91, in which it achieved a Suppression Rating of 61.5.
Relative Suppression Rating Performance is Summarized in SSS.7 - PEW Science Rankings
6.90.1 Resilient Suppressors RS9 Sound Signature Test Results
A summary of the principal Silencer Sound Standard performance metrics of the RS9 tested with the direct thread mount is shown in Table 1. The data acquired 1.0 m (39.4 in) left of the muzzle is available for viewing to all. This is a members-only review and includes pressure and impulse waveforms measured at the shooter’s ear. PEW Science thanks you for your support; further testing, research, and development of PEW-SOFT and the Silencer Sound Standard is made possible by members like you!
Table 1. Resilient Suppressors RS9 Sound Metric Summary
6.90.1.1 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 returned to battery with an empty chamber. The HK MP5 family of submachineguns do not possess a bolt-hold-open feature. 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 dataset and bolt-closing signatures. 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 Resilient Suppressors RS9 are shown in Figure 1a. The sound signatures of Shot 1, Shot 2, and Shot 3 are shown in Figure 1b, in early time. The real sound impulse (momentum transfer potential) histories from the same 5-shot test are shown in Figure 2a. In Figure 2b, a shorter timescale is shown comparing the impulse of Shot 1, Shot 2, and Shot 3.
Fig 1a. Resilient Suppressors RS9 subsonic 9x19mm HK SP5-A2 Semiautomatic Subgun Muzzle Sound Pressure Signature
Fig 1b. Resilient Suppressors RS9 subsonic 9x19mm HK SP5-A2 Semiautomatic Subgun Sound Pressure Signature
Figure 2a. Resilient Suppressors RS9 subsonic 9x19mm HK SP5-A2 Semiautomatic Subgun Muzzle Sound Impulse Signature
Figure 2b. Resilient Suppressors RS9 subsonic 9x19mm HK SP5-A2 Semiautomatic Subgun Muzzle Sound Impulse Signature
The Resilient Suppressors RS9 is highly specialized submachinegun silencer. In the current published dataset, there are performance characteristics of note. Additional performance context will be presented in future PEW Science Sound Signature Reviews. The reader should note the following:
The free field muzzle pressure signatures (Figure 1a) are presented, as typical, in accordance with the same data pedigree as the signatures presented for supersonic rifle silencers on the reciprocating standard PEW Science MK18 test host weapon system described in Public Research Supplement 6.51. The reciprocating standard PEW Science HK SP5-A2 test host weapon system is described in Public Research Supplement 6.85, and produces similar, albeit different, late-time phenomena (bolt closing signatures).
The muzzle pressure signature from the HK SP5-A2 is not as significantly suppressed with the RS9 (Figure 1) as it is with the GSL Phoenix (Review 6.86).
The rise-time to maximum positive phase impulse (Figure 3) from the RS9 is significantly faster than from the Phoenix. This gas behavior is indicative of less flow restriction (lower backpressure).
The first-round-pop (FRP) from the RS9 is nominally higher than from the larger Phoenix on the full-size HK SP5, to bystanders, in accordance with PEW Science inner ear modeling.
The performance of the RS9 on the full-size HK SP5 is significantly different than on the shorter-barrel HK SP5K-PDW system, on which the RS9 is evaluated in Sound Signature Review 6.91. The RS9 exhibits a highly atypical performance increase when used on shorter-barrel 9x19mm NATO host weapons. This phenomenon is investigated in that publication, in detail.
PEW Science Research Note 1: The ancillary combustion during Shot 1 is observed in both pressure space (Figure 1a) and impulse space (Figure 2a). 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 2: As in most semiautomatic 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 84 ms in Figure 1a) the mechanical noise of the bolt closing is observed. The pressure signature of Shot 6 still displays this event due to the bolt not remaining open after the sixth and final round is fired from the magazine on the HK SP5-A2 weapon system. Nonetheless, the bolt is closing on an empty chamber.
PEW Science Research Note 3: The closing time of the HK SP5-A2 bolt is directly related to the flow restriction of a silencer used with the 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 with rifle cartridges, particularly on the MK18 weapon system. PEW Science Omega Metric research in the subsonic 9x19mm combustion regime with the HK SP5-A2 and SP5K-PDW weapon systems is underway. Note that the PEW Science HK SP5-A2 possesses an 80-deg locking piece in its bolt carrier group, which may result in lower bolt carrier group rearward velocity than systems possessing standard angle locking pieces. This lower rearward velocity may result in delayed forward return velocity, when compared with other systems.
It is also important to note that PEW Science has determined bolt closing time to be an unreliable indicator upon upper receiver fouling in some weapon systems, such as the MK18. Sound signatures are typically not influenced by this fouling, as these kinematics occur in late time, after gas venting to atmosphere. Note that the roller-delayed blowback action of the HK SP5-A2 is significantly different than the direct gas impingement operated locked bolt action of the MK18. These factors, in addition to the difference in combustion regime amplitudes of supersonic 5.56x45mm and subsonic 9x19mm, result in a different influence of mechanical weapon noise to the total signature to which bystanders and the shooter is subjected.
As always, it is important to note that 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 semiautomatic firearm configuration.
PEW Science Research Note 4: Note that the muzzle Suppression Rating of the Resilient Suppressors RS9 with the direct thread mount is 52.5 and the shooter’s-ear Suppression Rating is 42.5; which are different zones on the Suppression Rating Dose Chart. The gross suppression of a silencer, as well as its flow rate, influences the holistic signature on the standard HK SP5-A2 weapon system. The signatures measured at the shooter’s ear are presented below.
6.90.1.2 SOUND SIGNATURES AT SHOOTER’S EAR
Real sound pressure histories from the same 6-shot test acquired with PEW-SOFT at the shooter’s ear are shown below. Again, 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 primary sound signature pressure histories at the ear for all 6 shots are shown in Figure 3. The primary sound signature history is shown in Figure 3a. A zoomed-in timescale is displayed in Figure 3b, in the region of peak sound pressure for Shot 1, Shot 2, and Shot 3. The real sound impulse (momentum transfer potential) histories at the ear from the same 6-shot test are shown in Figure 4. Again, full and short timescales are shown.
Figure 3a. Resilient Suppressors RS9 subsonic 9x19mm HK SP5-A2 Semiautomatic Subgun Ear Sound Pressure Signature
Figure 3b. Resilient Suppressors RS9 subsonic 9x19mm HK SP5-A2 Semiautomatic Subgun Ear Sound Pressure Signature, Short Time Window
Figure 4a. Resilient Suppressors RS9 subsonic 9x19mm HK SP5-A2 Semiautomatic Subgun Ear Sound Impulse Signature
Figure 4b. Resilient Suppressors RS9 subsonic 9x19mm HK SP5-A2 Semiautomatic Subgun Ear Sound Impulse Signature Peaks
The sound signatures measured at the shooter’s ear from a suppressed roller-delayed blowback submachine gun are complex. However, there are key waveform features that allow for strict interpretation of various events occurring during the gunshot, and their contribution to the overall signature.
PEW Science Research Note 5: Two primary factors differentiate the shooter’s-ear waveform signature compositions from a supersonic 5.56x45mm NATO automatic gas-operated rifle (the MK18) and a subsonic 9x19mm roller-delayed blowback submachine gun (the HK SP5 / MP5):
Overall combustion event amplitude and duration.
Weapon system kinematics; specifically lock time.
Many observations of the RS9 performance on the HK SP5-A2 are similar to that with the GSL Phoenix, including the time between combustion initiation and significant pressure pulse presented to the shooter’s ear from that combustion (prior to any gas from the silencer’s end-cap having time to reach the shooter). This time is still relatively short with the RS9, as it was with the Phoenix. The time regime may be examined in pressure space in Figure 3b and occurs from approximately 26.6 ms at initiation, peak internal combustion at approximately 27 ms, with a primary shock at approximately 27.1 ms; all three in less than a millisecond, total. The same phenomenon is observed in impulse space in Figure 4b. It is important to note that these events also occur in the unsuppressed firing of the HK MP5 system; they are characteristic of the host. Clear delineation of these events are possible due to (1) and (2), above, and through the use of PEW-SOFT. Note that, again, like with the Phoenix, the early-time combustion pulse from Shot 2 is significantly higher than that from other shots with the RSP (Figure 3b). This phenomenon influenced the inner ear response of the shooter to a greater degree than it did in the GSL Phoenix test.
PEW Science Research Note 6: Following the above, the deviation of signatures between the Resilient Suppressors RS9 and GSL Phoenix becomes more significant.
As was the case with the Phoenix, the sequence of events in the measured signatures from the RS9 become exceedingly complex after initial chamber combustion. Depending upon the silencer’s flow rate and suppression performance, the shooter’s ear is impacted by coalescing waves from multiple sources. The RS9 possesses a higher flow rate than the Phoenix and is slightly shorter; as a result, the RS9 produces a muzzle signature that propagates to the shooter’s position earlier in time (note the impulse accumulation beginning at approximately 29.5 ms in Figure 4b).
There is another significant signature deviation between the two silencers. The unlocking mechanics of the bolt carrier group occur differently with the Resilient Suppressors RS9 than they do with the GSL Phoenix. The amplitude and phase shifts of the unlocking signatures, coupled with the differing timing of the muzzle blast event coalescence, result in the RS9 producing a net reduction in signature severity to the shooter on this host weapon system. The RS9 is quieter than the Phoenix on the HK SP5-A2, to the shooter, despite being shorter and louder at the muzzle.
PEW Science Research Peer Review Notes: Internal engineering reviews and external engineering peer reviews have been conducted of PEW Science data on the HK SP5 system, focusing on weapon system kinematics. The roller movement and trunnion disengagement events are most likely the contributors at approximately 31 ms (Figure 4b) . Note that the bolt head is able to move prior to roller disengagement. Late-time event kinematics, such as cartridges being stripped from the magazine and the bolt returning to battery have also been verified (Figure 1a, 84 ms and Figure 3a, 82 ms).
Due to the relatively low amplitude and duration of subsonic 9x19mm combustion compared with supersonic 5.56x45mm combustion, the influence of the above signature factors on the holistic system signature, especially to the shooter, is more significant.
PEW Science Research Note 7: Unlike the case at the muzzle and to bystanders, the FRP from the Resilient Suppressors RS9 at the shooter’s ear on this weapon system is significantly suppressed. Elevated hearing damage risk to the shooter from FRP with the RS9 on this host is effectively nullified, in accordance with PEW Science inner ear modeling.
6.90.2 Suppression Rating Comparison (Subsonic 9x19mm from the HK SP5-A2)
Figure 5 presents a comparison of the PEW Science Suppression Rating of the Resilient Suppressors RS9 with the direct thread mount to that of the GSL Phoenix on the HK SP5-A2 system. RS9 performance data on the HK SP5K-PDW from Sound Signature Review 6.91 is also included, for comparison. The standard PEW Science HK SP5-A2 and HK SP5K-PDW test host weapon systems are described in Public Research Supplement 6.85.
Figure 5. Suppression Rating Comparisons of the Resilient Suppressors RS9 and GSL Phoenix on the HK SP5-A2 and SP5K-PDW, Using PEW-SOFT 9x19mm Subsonic Test Data and PEW Science Analysis
The performance of the Resilient Suppressors RS9, in the above context, is significant. Although the presented dataset in Figure 5 is not yet complete, there are significant conclusions that may be drawn:
The RS9 is slightly quieter than the GSL Phoenix (Review 6.86) on the HK SP5-A2, to the shooter, despite being shorter and louder at the muzzle. Although the RS9’s muzzle (bystander) Suppression Rating is a category lower than that of the Phoenix, it results in the same hearing damage risk to the weapon operator as the larger silencer. The RS9 possesses a higher flow rate (lower back pressure) than the GSL Phoenix.
In the unsuppressed state, the compact HK SP5K-PDW is a louder weapon than the full-size HK SP5-A2. This is shown, grossly, in Public Research Supplement 6.85 and in Figure 5, above. However, when suppressed, a silencer may change the relative nature of the sound signatures of these two weapon systems. Typically, a shorter-barreled system is louder than a longer-barreled system, all other things equal. However, the design of the RS9 results in increased sound suppression performance when subjected to the higher muzzle pressure produced by shorter-barrel 9x19mm NATO host weapons in the subsonic flow regime. This performance trait is highly atypical for a silencer. Detailed analysis of this phenomenon is presented in the analysis of the RS9 on the HK SP5K-PDW (Review 6.91). Future PEW Science data publications featuring other silencers on the short-barrel HK SP5K-PDW host weapon system will provide further performance context.
The PEW Science Suppression Rating quantifies inner ear damage risk. Human perception of sound may, or may not, always correlate. More detailed information regarding this phenomenon is presented periodically in PEW Science Member Research Supplements.
The signature to which the shooter’s ear is subjected is a function of both ejection port and muzzle signature. When the silencer’s endcap is in closer proximity to the shooter, the severity is increased. The coalescing of the ejection port overpressure with the primary muzzle blast exacerbates the severity of the signature at the shooter’s head position. It is not ejection port signature, alone, that dictates the signature measured at the shooter’s head position.
Significantly more barrel-length comparison data is provided in Section 6.91.3 of SSS6.91. The presentation and implications of this data and analysis in the subsonic 9x19mm combustion regime are novel and unprecedented. The Resilient Suppressors RS9 is therefore viewed by PEW Science to be a significant contribution to the submachinegun suppression state of practice.
PEW Science Research Caution: The reader is encouraged to be mindful of the following:
The Resilient Suppressors direct thread mount must be used with the RS9 to achieve the performance shown above.
The performance differential between the two barrel lengths is highly atypical. Higher performance on a shorter-barrel weapon is opposite to the performance trait of most, if not all, 9mm silencers on the current market. The RS9 is the only 9mm silencer tested by PEW Science, to date, that exhibits this performance trait. Results should not be extrapolated to other silencers.
6.90.3 Review Summary: Resilient Suppressors RS9 on the HK SP5 9x19mm Subgun with 8.9-in barrel
When paired with the 8.9-in barrel HK SP5-A2 with 80-deg locking piece and fired with Speer Lawman 147gr, the Resilient Suppressors RS9 mounted with the direct thread mount achieved a composite Suppression Rating™ of 53.1 in PEW Science testing. The 5.8-in barrel HK SP5K-PDW performance of the RS9 is detailed in Sound Signature Review 6.91, in which it achieved a Suppression Rating of 61.5. As with all weapon systems, the user is encouraged to examine both muzzle and ear Suppression Ratings.
PEW Science Subjective Opinion:
The Resilient Suppressors RS9 is a compact and lightweight submachinegun silencer that exhibits extremely high suppression performance at the shooter’s ear, for its size. The silencer possesses a unique performance trait of increased overall performance with higher muzzle pressure; a characteristic allowing higher performance on shorter-barreled host weapons. This performance trait is atypical of most silencers.
The RS9 is light and compact; it shares some physical traits with the RSP pistol silencer also manufactured by Resilient Suppressors. Both silencers use notched curved-cone baffles. Like in the RSP, there are specific design elements in the RS9 that allow for specialized performance. Both the piston assembly in the RSP and the direct thread mount included with the RS9 allow specialized venting of high pressure combustion gasses immediately after bullet uncorking. This venting, along with increased flow geometry and coaxial elements early in the stack, allow the silencers to manage early-time high pressure gas flow. In the subsonic projectile suppression regime, the principal benefit of this technology is higher flow rate. However, an ancillary benefit in the RS9 is enhanced performance as the input pressure increases. The RS9 possesses increased performance on the shorter-barreled HK SP5K-PDW when compared to the longer-barreled full-size HK SP5-A2. This performance differential is unprecedented in internal PEW Science testing and analysis to date, and represents a departure from currently accepted performance assumptions in this combustion regime. Therefore, PEW Science considers the RS9 technology to be a novel contribution to the submachinegun suppression state of practice. The implications of this performance paradigm shift may transfer to other flow regimes, which is a significant topic of future PEW Science research.
The Resilient Suppressors RS9 is user-serviceable; a welcome trait for a submachinegun silencer that may be subjected to significant firing schedules. The entirety of the baffle stack is heat treated 17-4 stainless steel, which also facilitates user-friendly maintenance. PEW Science highly recommends that users follow the manufacturer’s maintenance and care instructions.
The RS9 is rated for sustained fully automatic use on submachine gun platforms (9x19mm). It is important to note that the RS9 is not a rifle silencer and should not be used with rifle cartridges, subsonic 300 BLK notwithstanding.
The silencer may be attached to the host weapon with a variety of mount systems that use the so-called “HUB” mount threading of 1.375” x 24tpi. It is extremely important to note that the use of a mounting system with the RS9 other than the specialized Resilient Suppressors direct thread mount will change the performance of the RS9, sometimes significantly, depending on the host weapon.
Although the sound suppression performance, to the shooter, with the RS9 is high, care should be take by the weapon operator due to coupled muzzle blast and ejection port signature, as is the case on many, if not all, reciprocating suppressed small arm weapon systems. The Suppression Rating dose chart is intended to help guide users to understand the potential severity in accordance with their own personal risk tolerance.
In this review, the Resilient Suppressors RS9 performance metrics depend upon suppressing a subsonic centerfire pistol cartridge on a roller-delayed blowback submachinegun. While the sound signature of such cartridges can be suppressed to levels that may result in the desire of the shooter and bystanders to not wear hearing protection, PEW Science encourages the reader to remain vigilant with regard to all subsonic pistol cartridge suppression claims. The gas volume and combustion products created by firing a subsonic centerfire pistol cartridge such as 9x19mm are still significant; the measured pressure and impulse magnitudes, and their durations, illustrate this fact. Silencer performance on automatic (reciprocating) weapons depends on many factors. Weapon configuration may significantly influence total suppressed small arm system performance.
The hearing damage potential of subsonic submachinegun use is not insignificant. PEW Science encourages the reader to consider the Suppression Rating when deciding on an appropriate silencer and host weapon combination for their desired use.
