SSS.6.96 - HUXWRX CA$H 9K and the HK P30L
/HUXWRX CASH 9K on the HK P30L Full-Size Semiautomatic Pistol
The CA$H 9K is designed and manufactured by HUXWRX (formerly OSS). It is a 9mm centerfire silencer, intended to suppress many cartridges with projectiles appropriately sized to travel through the bore, up to and including .350 Legend. The CASH 9K has a 1.345-inch primary diameter and is 4.9 inches long. The silencer may be attached to a pistol with an internal inertial-decoupling piston possessing 1/2-28tpi or 13.5x1mm LH threading, which increases the length of the system to 5.4 inches. Other mounting options are possible due to the rear of the silencer body being threaded with the SilencerCo Alpha thread pattern. The so-called Flow-Baffles of the CA$H 9K, as well as the internal adapter cage, are constructed of 17-4 heat treated stainless steel. The end cap of the silencer is aluminum, and the tube body is titanium. The silencer is user-serviceable and weighs 8.0 ounces with the inertial-decoupling piston and spring assembly installed, as tested. The CASH 9K can be obtained from Silencer Shop.
PEW Science is an independent private testing laboratory and also the world’s only publicly funded suppressed small arms research cooperative. Testing, data analysis, and reporting is generated with funding provided by PEW Science members. Any test data that is generated with any portion of private funding contains this disclosure. The testing and data production for this Sound Signature Review was funded in part by PEW Science Project PEW-HUX-035-001-22. Therefore, data pertaining to the CA$H 9K in this Sound Signature Review is published with the express written permission of OSS Suppressors, LLC.
This Sound Signature Review contains single-test results using the HUXWRX CASH 9K on the HK P30L full-size semiautomatic pistol, chambered in 9mm with a 5-inch factory HK threaded barrel. Speer Lawman 147gr ammunition was used in the test.
Section 6.96.1 contains the CA$H 9K test results and analysis.
Section 6.96.2 contains Suppression Rating comparisons of the CASH 9K with the Resilient Suppressors RSP, CGS MOD9 FS, Rugged Obsidian 45, and SWR Trident-9 silencers, fired on the Heckler and Koch P30L.
Section 6.96.3 contains the review summary and PEW Science subjective opinions.
Summary: When paired with the HK P30L full-size semiautomatic pistol and fired with Speer Lawman 147gr ammunition, the HUXWRX CA$H 9K achieved a Suppression Rating™ of 45.3 in PEW Science testing. As with all weapon systems, the user is encouraged to examine both muzzle and ear Suppression Ratings.
The submachinegun (PCC) performance of the HUXWRX CA$H 9K on the HK SP5 is detailed in Sound Signature Review 6.97, in which it achieved a Suppression Rating of 47.8.
Relative Suppression Rating Performance is Summarized in SSS.7 - PEW Science Rankings
6.96.1 HUXWRX CASH 9K Sound Signature Test Results
A summary of the principal Silencer Sound Standard performance metrics of the CA$H 9K tested on the HK P30L 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. HUXWRX CA$H 9K Sound Metric Summary
6.96.1.1 SOUND SIGNATURES AT THE MUZZLE
Real sound pressure histories from a 6-shot test acquired with PEW-SOFT™ are shown below. Six cartridges were loaded into the magazine and the weapon was fired until the magazine was empty, and the slide locked back on the slide-release lever actuated by the follower of the empty magazine. Only five shots are considered in the analysis. The signatures of Shot 6 are displayed in the data presentation but are not included in the analysis to maintain consistency with the overall PEW Science dataset. The waveforms are not averaged, decimated, or filtered. The data acquisition rate used in all PEW Science testing is 1.0 MS/s (1 MHz). The peaks, shape, and time phasing (when the peaks occur in relation to absolute time and to each other) of these raw waveforms are the most accurate of any firearm silencer testing publicly available. PEW-SOFT data is acquired by PEW Science independent testing; the industry leader in silencer sound research. For more information, please consult the Silencer Sound Standard.
The primary sound signature pressure histories for all 6 shots with the HUXWRX CA$H 9K 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 through Shot 4.
Fig 1a. HUXWRX CA$H 9K subsonic 9x19mm HK P30L Semiautomatic Pistol Muzzle Sound Pressure Signature
Fig 1b. HUXWRX CA$H 9K subsonic 9x19mm HK P30L Semiautomatic Pistol Sound Pressure Signature
Figure 2a. HUXWRX CA$H 9K subsonic 9x19mm HK P30L Semiautomatic Pistol Muzzle Sound Impulse Signature
Figure 2b. HUXWRX CA$H 9K subsonic 9x19mm HK P30L Semiautomatic Pistol Muzzle Sound Impulse Signature
PEW Science Technology Note: The following is a description of silencer technology derived from PEW Science research: The OSS / HUXWRX Flow-Through technology used in HUXWRX rifle silencers achieves efficacy by routing combustion gasses through overlapping annular paths, axially forward and aft, and finally exhausting these gasses through distal vents, to atmosphere. This gas management begins in early time, in conjunction with the primary flow through the bore. The suppression performance efficiency of HUXWRX rifle silencers is therefore directly proportional to combustion pressure and duration. As pressure and duration drop, the proportion of flow occupying the primary bore increases; this decreases suppression efficiency of the Flow-Through technology. This phenomenon is demonstrated in the testing and analysis of the HUXWRX OSS HX-QD 762 in the supersonic 7.62x51mm combustion regime (Review 6.41) and the respective review of the same silencer in the subsonic 300 BLK combustion regime (Review 6.45). The silencer is shown to lose efficiency when suppressing the subsonic 300 BLK cartridge.
The subsonic 9x19mm pistol cartridge shares some characteristics with that of the subsonic 300 BLK cartridge referenced above; namely lower combustion pressure and duration. In order for the Flow-Through technology to achieve efficacy within these combustion parameters, it must be fully accessed in the time regime of interest. Therefore, the HUXWRX CASH 9K does not utilize the same Flow-Through technology; instead, it uses the HUXWRX Flow-Baffle. The Flow-Baffle is a hybrid internal design in which combustion gasses are still routed immediately to an outer annulus for later distal venting. However, the principle differentiator between this technology and the rifle technology is the presence of traditional baffle geometry along the primary bore path. With a shorter annular path and a traditional baffle core, the Flow-Baffle is able to manage lower pressure combustion products immediately and over a shorter duration. PEW Science postulates that scaling traditional Flow-Through design for use with subsonic 9x19mm cartridge would be inefficient and that the hybrid Flow-Baffle design produces greater efficiency in this regime. Current PEW Science test data and analysis strongly supports this postulation.
PEW Science Analytical Discussion: The HUXWRX CASH 9K possesses a relatively high flow rate, compared to most pistol silencers on the current market. This design performance characteristic results in some unique performance factors, similar to that observed with the Resilient Suppressors RSP (Review 6.87). Several signature characteristics of the CASH 9K measured at the muzzle highlight key differences from other silencers tested by PEW Science, to date, on the full-size HK P30L semiautomatic host weapon. These characteristics include:
The flow rate of the CASH 9K is even higher than that of the RSP; the backpressure of the CASH 9K is lower. In addition to its higher flow rate, the CASH 9K is also shorter. The immediate consequences of these design features are evident in the early-time jetting in Figure 1b, as well as the prolonged positive pressure phase; rarefaction is not significant after First-Round-Pop (FRP) until approximately 30.4 ms.
Like in the case of the RSP, the HUXWRX CASH 9K exhibits relatively uniform combustion characteristics in both pressure space (Figure 1) and impulse space (Figure 2). Note that the precursor and bullet exit pressure waves are coincident due to the higher flow rate. The rates of impulse rise and decay in Figure 2a are extremely high; a trait shared among various HUXWRX and OSS silencers across various host weapon platforms due to so-called Flow-Through technology. This is, again, indicative of extremely low back pressure for the platform. This behavior is further confirmed, holistically, by the signature measured at the shooter’s ear and the shooter’s-ear Suppression Rating.
PEW Science Research Note 1: The HUXWRX CASH 9K does have significant FRP to bystanders on this platform. In addition to the more significant ancillary combustion during Shot 1 observed in both pressure space (Figure 1a) and impulse space (Figure 2a), the onset of this ancillary combustion occurs very early in time. This early-onset FRP, that remains prolonged post-peak, is primarily a consequence of the silencer’s technology being employed in a relatively short overall length. As discussed above, the backpressure-reducing features of the HUXWRX CASH 9K are somewhat similar to its rifle silencer counterparts from HUXWRX / OSS. However, due to the combustion pressure and duration produced by many pistol cartridges, more conventional features are present in HUXWRX’s Flow-Baffles than in their Flow-Through rifle silencer internal designs. The Flow-Baffles used in the CASH 9K are typical notched curved cones, but facilitate annular space between the outer baffle wall and the inner diameter of the silencer’s tube. This space, in conjunction with helical fins, facilitate high flow immediately and this flow is maintained through distal venting. Therefore, the FRP propagation is only marginally reduced.
PEW Science Research Note 2: Like with many silencers used on semiautomatic centerfire handguns, the HUXWRX CASH 9K produces semi-random early time pressure shocks on the HK P30L semiautomatic pistol. This phenomenon manifests in both the waveforms measured at the muzzle (29.7 ms, Shot 5, Fig 2b) and in the waveforms measured at the shooter’s ear. This measured early-time shock load is postulated by PEW Science to result from a possible pressure leak from the breach of the locked semiautomatic HK P30L pistol. This phenomenon also occurred in the PEW Science tests of the aforementioned Resilient Suppressors RSP, the SWR Trident-9 (Review 6.8), the Rugged Obsidian 45 in both long and short configurations (Review 6.7), and the CGS MOD9 FS (Review 6.6). Interestingly, the phenomenon occurs less frequently with the CASH 9K; this shock occurred only during Shot 5 in this test, which was one of the quietest shots to bystanders, in accordance with PEW Science inner ear response analyses. Somewhat unique to the phenomenon observed in this test is the subsequent pressure delay measured at the muzzle after this event. This delayed onset of primary jetting, as notated in Figure 2b, may be a result of a gas leak from early unlock. Factors contributing to this phenomenon are the subject of internal PEW Science research.
PEW Science Research Note 3: 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 75 ms in Figure 1a) the mechanical noise of the slide closing is observed. The pressure signature of Shot 6 does not display this event due to the slide remaining locked to the rear after the sixth and final round is fired from the magazine.
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 HUXWRX CASH 9K used on the full-size HK P30L semiautomatic handgun test host is 38.6 and the shooter’s-ear Suppression Rating is 43.8 ; 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 a semiautomatic host weapon. The signatures measured at the shooter’s ear are presented below.
6.96.1.2 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 5. 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. HUXWRX CA$H 9K subsonic 9x19mm HK P30L Semiautomatic Pistol Ear Sound Pressure Signature
Figure 3b. HUXWRX CA$H 9K subsonic 9x19mm HK P30L Semiautomatic Pistol Ear Sound Pressure Signature, Short Time Window
Figure 4a. HUXWRX CA$H 9K subsonic 9x19mm HK P30L Semiautomatic Pistol Ear Sound Impulse Signature
Figure 4b. HUXWRX CA$H 9K subsonic 9x19mm HK P30L Semiautomatic Pistol Ear Sound Impulse Signature Peaks
Immediate differences between the signature measured at the shooter’s ear from the CASH 9K and other silencers, including from the Resilient Suppressors RSP, are noted in the pressure waveforms (Figure 3) and impulse waveforms (Figure 4), above. Note the extremely fast blow-down evident at the shooter’s ear (the low pressure amplitude during all shots at approximately 35 ms, Figure 3a). This is a consequence of the extremely high flow rate (low back pressure) of the CASH 9K.
PEW Science Research Note 5: The early-time shock load occurring during Shot 5, previously discussed above, is plainly visible in Figure 3 and Figure 4. Note the early time combustion signatures in Figure 3b; at approximately 27.5 ms, combustion initiation occurs uniformly, from shot to shot. The subsequent shock load during Shot 5 is therefore not a late-time phenomenon manifesting earlier due to data acquisition timing, but is actually an early-time pulse from ejection port combustion prior to complete combustion. This conclusion is further reinforced by the coincident positive phase impulse accumulation at approximately 29.6 ms in Figure 4b. PEW Science postulates that the so-called modified tilting-barrel Browning action present in many modern semiautomatic handguns is susceptible to this phenomenon due to its locking resistance early in the displacement-time kinematic cycle. PEW Science further postulates that this phenomenon may be more prevalent during the use of pistol silencers exhibiting relatively higher early-time flow restriction (back pressure). The CASH 9K signatures exhibit this phenomenon less so than other silencers tested by PEW Science on this platform, as stated previously. It is also interesting to note that Shot 5 was the loudest to the shooter in this test, excluding FRP. To bystanders, Shot 5 was the quietest of the first five shots.
PEW Science Research Note 6: The lack of flow restriction (back pressure) from the HUXWRX CASH 9K, compared to other silencers tested on the HK P30L by PEW Science, is significant. As stated in the preceding section, the CASH 9K possesses signature features consistent with this behavior. At the shooter’s ear, the signatures share many characteristics with those of the Resilient Suppressors RSP and the Rugged Obsidian 45 in its short configuration (Review 6.7). And, like the short configuration of the Obsidian 45, the CASH 9K does exhibit significant FRP to both bystanders and the shooter. This is a consequence of the design of the two silencer configurations:
The short configuration of the Obsidian 45 has very few baffles, which are of conventional design. These baffles are also significantly over-bored for the 9mm cartridge. Propagation of ancillary combustion is significant through this geometry.
The CASH 9K is also a short silencer, like the short configuration of the Obsidian 45, and exhibits immediate venting to reduce backpressure, like the RSP. However, in contrast with the RSP, the CASH 9K utilizes direct venting through the entire silencer length. It is through this annular path that the FRP propagates. Although the helical machined features on the outer baffle walls interact with gas flow, pistol cartridge combustion is of relatively short duration and suppression efficiency somewhat drops.
Despite some inefficiencies, the HUXWRX CASH 9K suppresses significantly at the shooter’s ear on this platform, especially for its compact size.
The advantage of the CASH 9K’s flow rate (low back pressure) is evident in the comparison of its performance on this system with the other silencers, as shown in the following section.
6.96.2 Suppression Rating Comparison (Subsonic 9x19mm from the HK P30L)
Figure 5 presents a comparison of the PEW Science Suppression Rating of the HUXWRX CASH 9K with other silencers on the full-size HK P30L semiautomatic pistol using subsonic Speer Lawman 147gr 9mm ammunition.
Figure 5. Suppression Rating Comparisons of the HUXWRX CA$H 9K with the Resilient Suppressors RSP, Rugged Obsidian 45, CGS MOD9 FS, and SWR Trident-9 on the HK P30L, Using PEW-SOFT 9x19mm Subsonic Test Data and PEW Science Analysis
Readers may immediately note the performance delta at the shooter’s ear between the HUXWRX CASH 9K and the other silencers shown. Like the Resilient Suppressors RSP (Review 6.87), the CASH 9K exhibits significantly reduced backpressure relative to other 9mm pistol silencers. In fact, the CASH 9K exhibits signature and flow rate characteristics similar to that of the Rugged Obsidian 45 in its short configuration (Review 6.7). The HUXWRX CASH 9K is able to produce reduced hearing damage risk to the shooter, in a shorter overall length, than many pistol silencers. The suppression performance of the CASH 9K, for its size, is notable on this platform.
The Resilient Suppressors RSP does exhibit higher performance at the shooter’s ear than the HUXWRX CASH 9K, but the RSP is longer than the CASH 9K and therefore its end cap is further away from the shooter’s head. The CASH 9K exhibits higher performance 1.0 m left of the end cap than the RSP; again, a noteworthy performance trait for its size, on this platform.
Both the CASH 9K and RSP utilize more advanced designs than other high flow rate conventional configurations like the short configuration of the Rugged Obsidian 45 (Review 6.7). The Rugged Obsidian 45 exhibits a relatively high flow rate when used on 9mm host weapons due to over-bore. This performance-based design comparison is similar to that made by PEW Science when examining the performance of high flow-rate silencers on the MK18 (over-bored 30 caliber silencers vs. dedicated-bore 5.56x45mm silencers with advanced porting or flow paths).
The HUXWRX CASH 9K is significantly louder to bystanders, on average, than the long configuration of the Rugged Obsidian 45, the CGS MOD9 FS (Review 6.6), and the SWR Trident-9 (Review 6.8). However, the CASH 9K possesses a very high shooter’s-ear Suppression Rating on the HK P30L, and therefore more significantly reduces hearing damage risk, to the shooter, than those silencers. Although the FRP from the CASH 9K is significant, its performance, on average, is notable for its size.
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.
6.96.3 Review Summary: HUXWRX CA$H 9K on the HK P30L Full-Size Semiautomatic Pistol
When paired with the HK P30L full-size semiautomatic pistol and fired with Speer Lawman 147gr ammunition, the HUXWRX CASH 9K achieved a Suppression Rating™ of 45.3 in PEW Science testing. The submachinegun (PCC) performance of the HUXWRX CA$H 9K on the HK SP5 is detailed in Sound Signature Review 6.97, in which it achieved a Suppression Rating of 47.8. As with all weapon systems, the user is encouraged to examine both muzzle and ear Suppression Ratings.
PEW Science Subjective Opinion:
The HUXWRX CA$H 9K is a compact 9mm pistol silencer that exhibits extremely low backpressure. At 8.0 ounces and 5.9 inches long, the CASH 9K is lighter and smaller than many other 9mm pistol silencers on the current market, while also exhibiting superior sound signature suppression to the shooter, using a full-size semiautomatic handgun. The holistic design and performance of the CA$H 9K is notable, especially for its size.
The backpressure-reducing features of the HUXWRX CASH 9K are somewhat similar to its rifle silencer counterparts from HUXWRX / OSS. However, due to the combustion pressure and duration produced by many pistol cartridges, more conventional features are present in HUXWRX’s “Flow-Baffles” than in their “Flow-Through” rifle internal designs. Nonetheless, the Flow-Baffle technology does show efficacy in the subsonic pistol cartridge combustion regime, as evidenced by the data and analysis in this test report. PEW Science postulates that systems most sensitive to silencer back pressure stand to gain the most performance benefit from this technology. Semiautomatic pistols often exhibit significant “port pop” to the shooter; this phenomenon is significantly reduced by silencers like the HUXWRX CASH 9K, the Resilient Suppressors RSP, and over-bored or short pistol silencers. Increased flow rate (reduced back pressure) of silencers used on semiautomatic centerfire handguns is paramount to signature reduction performance to the weapon system operator. The analysis of the data in this report again confirms the conclusion by PEW Science that over-bore or simple baffle reduction is often less efficient for balancing flow rate and suppression; the HUXWRX technology provides greater effectiveness.
Users should note that bystanders will be subjected to a higher hearing damage risk with the CASH 9K than with some other high-performance centerfire pistol silencers. This difference in muzzle Suppression Rating is a consequence of the CASH 9K’s flow rate and very compact size. For context, on average, the short configuration of the Rugged Obsidian 45 possesses similar performance on this host, to bystanders.
HUXWRX states that the CASH 9K is rated for fully-automatic fire with the cartridges of interest (9mm and 300 BLK subsonic). Although PEW Science has not evaluated the durability of the CASH 9K, its high flow rate is most likely a welcome performance attribute for its use on such systems. It is postulated that its stainless steel baffles are also resilient enough for this use.
Disassembly of the CASH 9K with the included tool is relatively simple; the tool can be used to remove both the included direct-thread mount and the silencer’s end cap. The use of other mounting systems is possible. Successful operation of the CASH 9K on a semiautomatic handgun is possible with the rear piston retainer and piston from a SilencerCo Omega 9K, for example.
Of particular note is the small size and relatively light weight of the HUXWRX CASH 9K. At 8.0 ounces and 5.4 inches long with a piston mount, its performance in the design envelope is notable.
In this review, the HUXWRX CASH 9K performance metrics depend upon suppressing a full-size combat handgun firing a full-power subsonic centerfire pistol cartridge. This type of evaluation provides a potential upper-bound for typical real handgun silencer performance due to the barrel length and action dynamics of the host weapon. PEW Science encourages the reader to carefully consider action dynamics, barrel lengths, and other characteristics in the selection of centerfire pistol silencer hosts.
The hearing damage potential of centerfire pistol 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. Note that the presence of nearby reflecting surfaces, as well as ammunition choice, can influence the sound signature to which both the shooter and bystanders are subjected.
