SSS.6.91 - Resilient Suppressors RS9 and the Heckler and Koch SP5K-PDW 9x19mm PDW Subgun (Free Version)
/Resilient Suppressors RS9 on the HK SP5K-PDW 9x19mm Subgun with 5.8-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 SP5K-PDW subgun, chambered in 9x19mm NATO with a 5.8-inch barrel. Speer Lawman 147gr ammunition was used in the test, in which its velocity was subsonic. The standard PEW Science HK SP5K-PDW test host weapon system is described in Public Research Supplement 6.85.
Section 6.91.1 contains the RS9 test results and analysis.
Section 6.91.2 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. The HK SP5-A2 RS9 data is presented in SSS6.90.
Section 6.91.3 contains the review summary and PEW Science subjective opinions.
Summary: When paired with the 5.8-in barrel HK SP5K-PDW 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 61.5 in PEW Science testing. As with all weapon systems, the user is encouraged to examine both muzzle and ear Suppression Ratings.
The 8.9-in barrel HK SP5-A2 performance of the RS9 is detailed in Sound Signature Review 6.90, in which it achieved a Suppression Rating of 53.1.
Relative Suppression Rating Performance is Summarized in SSS.7 - PEW Science Rankings
6.91.1 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. 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 1. Resilient Suppressors RS9 Sound Metric Summary
6.91.1.1 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 SP5K-PDW Semiautomatic Subgun Muzzle Sound Pressure Signature
Fig 1b. Resilient Suppressors RS9 subsonic 9x19mm HK SP5K-PDW Semiautomatic Subgun Sound Pressure Signature
Figure 2a. Resilient Suppressors RS9 subsonic 9x19mm HK SP5K-PDW Semiautomatic Subgun Muzzle Sound Impulse Signature
Figure 2b. Resilient Suppressors RS9 subsonic 9x19mm HK SP5K-PDW 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 SP5K-PDW test host weapon system is described in Public Research Supplement 6.85, and produces similar, albeit different, late-time phenomena (bolt closing signatures).
The performance of the RS9 on the shorter-barrel HK SP5K-PDW system is significantly different than on the full-size HK SP5 system, holistically. The RS9 exhibits a highly atypical performance increase when used on shorter-barrel 9x19mm NATO host weapons.
The muzzle pressure signature from the HK SP5K-PDW is suppressed to a greater degree than the signature from the full-size HK SP5-A2 with the RS9. Please reference previous Review 6.90 with the RS9 on the HK SP5-A2. This performance differential is highly atypical and further examined with detailed signature comparisons in Section 6.91.3 of this review.
The rate of rise to to maximum positive phase impulse (Figure 2) from the RS9 on the SP5K-PDW is reduced when compared to that from the RS9 on the SP5-A2. This represents more efficient trapping of combustion gasses with higher pressure flow, and is also further described in Section 6.91.3 of this review.
The first-round-pop (FRP) from the RS9 is nominally reduced on the shorter-barreled HK SP5K-PDW when compared to that on the full-size HK SP5, in accordance with PEW Science inner ear modeling. This is also highly atypical.
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 SP5K-PDW weapon system. Nonetheless, the bolt is closing on an empty chamber.
PEW Science Research Note 3: The closing time of the HK SP5K-PDW 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 both the PEW Science HK SP5-A2 and HK SP5K-PDW host weapons possess 80-deg locking pieces in their bolt carrier groups, 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 SP5K-PDW 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 on the HK SP5K-PDW with the direct thread mount is 61.5 and the shooter’s-ear Suppression Rating is 41.9; which are significantly 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 and HK SP5K-PDW weapon systems. The holistic signatures quantified by the Suppression Rating are compared, below.
6.91.2 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 on both the HK SP5-A2 and HK SP5K-PDW weapon systems to that of the GSL Phoenix on the HK SP5-A2 system. RS9 performance data on the HK SP5-A2 data is provided in SSS6.90. GSL Phoenix HK SP5-A2 data is provided in SSS6.86. 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 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 on the HK SP5-A2 (Review 6.86), 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 below in Section 6.91.3. 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.
Below is a detailed comparison of RS9 muzzle signatures from two different barrel lengths (the full size SP5 and the PDW). It is important to note that the relative comparisons below are highly atypical.
6.91.3 Detailed Muzzle Signature Comparison (Subsonic 9x19mm from the HK SP5-A2 and HK SP5K-PDW)
Figure 6a presents the first round sound signatures of the Resilient Suppressors RS9 silencer on the full-size HK SP5-A2 and compact HK SP5K-PDW, respectively, in pressure space. The same comparison is shown in impulse space, in Figure 6b.
Figure 6a. Resilient Suppressors RS9 subsonic 9x19mm HK SP5-A2 and HK SP5K-PDW Semiautomatic Subgun Muzzle Pressure Signature Comparison (Shot 1)
Figure 6b. Resilient Suppressors RS9 subsonic 9x19mm HK SP5-A2 and HK SP5K-PDW Semiautomatic Subgun Muzzle Impulse Signature Comparison (Shot 1)
The waveforms measured with the HK SP5K-PDW have been shifted in time, as noted, to allow coincident comparison with combustion events from the two systems. The noted time-shift is also adequate for data pedigree verification, as the dimensions of the weapon systems and measurement locations are published.
The principal differences illustrated during FRP with the two systems are the signature amplitudes (Figure 6a and Figure 6b) and impulse accumulation rate (Figure 6b). The impulse accumulation rate shown is a direct illustration of the RS9’s ability to more efficiently trap combustion gasses with higher pressure flow. This is shown by the shallower initial slope of the red curve in Figure 6b.
The performance differential of the Resilient Suppressors RS9 with higher muzzle pressure is not limited to FRP. It also occurs during subsequent shots. This is presented for Shot 2, below.
Figure 7a. Resilient Suppressors RS9 subsonic 9x19mm HK SP5-A2 and HK SP5K-PDW Semiautomatic Subgun Muzzle Pressure Signature Comparison (Shot 2)
Figure 7b. Resilient Suppressors RS9 subsonic 9x19mm HK SP5-A2 and HK SP5K-PDW Semiautomatic Subgun Muzzle Impulse Signature Comparison (Shot 2)
Figure 7 presents the second round sound signatures of the Resilient Suppressors RS9 silencer on the full-size HK SP5-A2 and compact HK SP5K-PDW, respectively. Again, the comparison is made in both pressure space (Figure 7a) and impulse space (Figure 7b). Although the performance differential during Shot 2 is not as great as it is during FRP, the RS9 is still able to create a situation in which the HK SP5K-PDW outperforms the HK SP5-A2 in suppression, in subsequent shots. This performance differential is present in all shots fired with the RS9 on these weapon systems. The same shallower impulse accumulation rate noted during FRP in Figure 6b is shown during Shot 2 in Figure 7b. The above data indicates that the RS9 traps gas more efficiently with higher pressure combustion, all other things equal.
The practical implications of the analysis in this review, holistically, are that the Resilient Suppressors RS9 is a high flow rate silencer that operates well enough with high pressure, that when paired with a short-barrel submachinegun, is able to out-perform many traditional silencer designs on full-size submachineguns. Its high performance with higher pressure flow, coupled with its high flow rate, trips the performance balance to its favor.
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.
6.91.4 Review Summary: Resilient Suppressors RS9 on the HK SP5K-PDW 9x19mm Subgun with 5.8-in barrel
When paired with the 5.8-in barrel HK SP5K-PDW 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 61.5 in PEW Science testing. The 8.9-in barrel HK SP5-A2 performance of the RS9 is detailed in Sound Signature Review 6.90, in which it achieved a Suppression Rating of 53.1. 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.
