SSS.6.6 - CGS MOD9 FS and the HK P30L
/CGS MOD9 FS on the HK P30L Full-Size Semiautomatic Pistol
The MOD9 Full-Size (FS) is manufactured by CGS Group. It is a 9mm centerfire pistol silencer, intended to suppress many cartridges with projectiles appropriately sized to travel through the bore, up to and including subsonic 300BLK. It has a 1.37-inch diameter and is 7.7 inches in length. The silencer mounts to the host firearm with an internal inertial decoupling piston assembly available in multiple standard thread pitches. The silencer outer tube and primary baffles are constructed of 7075-T6 aluminum, while the blast baffle is constructed of 17-4 stainless steel. The silencer is user-serviceable and weighs 10 ounces. The MOD9 FS can be obtained from Silencer Shop.
This review contains single-test results using the MOD9 FS 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.
Summary: When paired with the HK P30L full-size semiautomatic pistol and fired with Speer Lawman 147gr ammunition, the CGS MOD9 FS achieved a Suppression Rating™ of 55.4 in PEW Science testing.
6.6.1 CGS MOD9 FS Sound Signature Test Results
A summary of the principal Silencer Sound Standard performance metrics of the MOD9 FS 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. CGS MOD9 FS Sound Metric Summary
6.6.1.1 SOUND SIGNATURES AT THE MUZZLE
Real sound pressure histories 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.
Figure 1 shows the first round sound pressure signature of the CGS MOD9 FS as measured 1.0 m left of the muzzle, in a total time scale of 25 milliseconds. There are three significant peak events labeled:
An initial gas pulse out of the silencer causes a 133.5 dB peak.
As gas continues to exit the silencer from the primary combustion event, the measured sound pressure rises to a maximum of 140.8 dB.
After the silencer’s inertial decoupling system (piston assembly) and slide re-seat and the slide returns to battery, action-noise results in a peak of 125.6 dB.
This is the typical sequence observed when firing subsonic 9mm ammunition from the HK P30L semiautomatic pistol with an attached silencer; however, internal silencer design and piston assembly design can significantly influence the measured pressure amplitudes and timing.
Fig 1. CGS MOD9 FS First Round HK P30L Muzzle Sound Pressure Signature, 18-APR-2020
Closer views of the first peak (Fig 2a) and second peak (Fig 2b) are shown below. Figure 2a illustrates the time prior to primer ignition and early-time sound signature of weapon function, followed by the initial gas pulse. Figure 2b shows points later in time as the maximum sound pressure occurs from the primary combustion event; note that the total timescale is only 0.06 milliseconds (60 microseconds). PEW-SOFT provides a sampling point every microsecond and the individual data points are shown to illustrate this.
Fig 2a. CGS MOD9 FS First Round HK P30L Muzzle Sound Pressure Peak 1, 18-APR-2020
Fig 2b. CGS MOD9 FS First Round HK P30L Muzzle Sound Pressure Peak 2, 18-APR-2020
The primary sound signature pressure histories for all 5 shots with the MOD9 FS are shown in Figure 3a. The sound signature of Shot 2 is shown alone in Figure 3b. Note the same three peak events are labeled for Shot 2 that were previously labeled for Shot 1, above. The real sound impulse (momentum transfer potential) histories from the same 5-shot test are shown in Figure 4a. In Figure 4b, a shorter timescale is shown comparing the impulse of Shot 1 to that of Shot 4.
Fig 3a. CGS MOD9 FS HK P30L Muzzle Sound Pressure Signature, 18-APR-2020
Fig 3b. CGS MOD9 FS Second Round HK P30L Muzzle Sound Pressure Signature, 18-APR-2020
Figure 4a. CGS MOD9 FS HK P30L Muzzle Sound Impulse Signature, 18-APR-2020
Figure 4b. CGS MOD9 FS HK P30L Muzzle Sound Impulse Signature, 18-APR-2020
The measured pressure regime first-round-pop (FRP) is evident when comparing Shot 1 (Fig 1) to Shot 2 (Fig 3b). Figure 4a also shows FRP in the impulse regime. Note that Shot 1 and Shot 4 both possess higher early-time gas pulses which resulted in earlier PEW-SOFT triggering time. This is clearly illustrated in Fig 4a; the impulse histories for the other three shots are shifted in time by approximately 1 millisecond. The reason for the data acquisition triggering time discrepancy between the two shot groups (Shots 1 and 4 vs. Shots 2, 3, and 5) is the differing sound signature between the two groups characterized by the aforementioned higher early-time gas pulses. The behavior of the MOD9 FS in this test and this somewhat erratically occurring (but consistent in impulse amplitude) early-time gas pulse can easily be seen in the sharp initial impulse rise of Shots 1 and 4 beginning at a time of approximately 29.9 milliseconds (Fig 4b).
The combination of the measured timing of sound pressure peaks and the peak impulse timing indicates that the FRP behavior of the silencer measured at the muzzle is not a result of the event occurring at the earliest peak. Therefore, the early-time peaks in Shot 1 and Shot 4 may result from events other than sustained combustion. Waveforms measured at the shooter’s ear indicate that this early-time peak event is non-trivial (PEW Science members can read the continuation of this discussion in the following section). Regardless of this measured early-time phenomenon, the overall shape of the impulse waveforms measured at the muzzle, from shot-to-shot, are extremely consistent, highlighting 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 note: 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.
6.6.1.2 SOUND SIGNATURES AT SHOOTER’S EAR
Real sound pressure histories from the same 5-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 measured at the ear for all 5 shots are shown in Figure 5. The primary sound signature history is shown on the left. A zoomed-in timescale is displayed on the right, in the region of peak sound pressure showing three of the five shots. The real sound impulse (momentum transfer potential) histories at the ear from the same 5-shot test are shown in Figure 6.
Figure 5a. CGS MOD9 FS HK P30L Ear Sound Pressure Signature, 18-APR-2020
Figure 5b. CGS MOD9 FS HK P30L Ear Sound Pressure Signature, Short Time Window, 18-APR-2020
Figure 6a. CGS MOD9 FS HK P30L Ear Sound Impulse Signature, 18-APR-2020
Figure 6b. CGS MOD9 FS HK P30L Ear Sound Impulse Signature Peaks, 18-APR-2020
The previously observed FRP characteristics measured at the muzzle are evident in the ear measurements in the shape of the overall impulse signatures shown in Figure 6a with the large impulse rise and duration for Shot 1. However, measured at the ear, Shot 4 possesses both the highest peak pressure (Figure 5b) and the highest peak impulse (Figure 6b).
The early-time pressure pulses measured at the muzzle during Shot 1 and Shot 4 (shown in the previous section) are much more easily observed in the measurements at the ear. These events occur at the ear at approximately 28.8 ms, which is approximately a millisecond sooner than their occurrence in the muzzle measurements. It is postulated that this may indicate an anomaly in weapon action dynamics.
The overall sound signature measured at the shooter’s ear possesses a higher peak average pressure amplitude than that measured at the muzzle but a lower peak average impulse (refer to Table 1). Although FRP is not noted at the ear in the traditional sense when examining the absolute peak pressure and impulse magnitudes of Shot 1, it it is important to note that the impulse signatures shown in Figure 6a indicate a clear FRP at the ear when considering the duration of potential momentum transfer. When examining the details of theoretical physical human inner ear response to these sound signatures, the FRP is clearly present. That analysis will be presented in a future PEW Science member research supplement.
6.6.2 Review Summary: CGS MOD9 FS 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 CGS MOD9 FS achieved a Suppression Rating™ of 55.4 in PEW Science testing.
PEW Science Subjective Opinion:
The CGS MOD9 FS is a high performing 9mm pistol silencer intended for semiautomatic handgun use. The internal piston assembly functions reliably and possesses physical features that may enhance suppression performance; evaluation of those features is a subject of continued research interest. The silencer does possess First Round Pop (FRP) which manifests itself in not only measured sound pressure and impulse, but in calculated physical human ear response (the FRP is analytically predicted to be noticeable to the unprotected human ear and this conclusion agrees with PEW Science anecdotal observation).
The MOD9 FS is relatively light weight for a full-size pistol silencer which is due to the tube and primary baffle stack being constructed of aluminum, rather than stainless steel. It is important to note that the blast baffle (the first baffle in the stack) is constructed of stainless steel, which is a favorable characteristic for a centerfire pistol silencer. Unburned pistol powder and combustion products generated during use on centerfire handguns may damage less resilient silencer blast baffle materials, such as aluminum. This potential wear can be exacerbated with fixed barrel weapons, the use of which may dictate more aggressive firing schedules. The MOD9 FS is intended for pistol use, however, it may possess requisite durability for dual-use on pistol caliber carbines and it is also rated by the manufacturer for use on subsonic 300BLK. Durability of the silencer during aggressive firing schedules on fixed barrel weapons has not been evaluated by PEW Science. Note that a fixed-barrel-spacer must be used in lieu of the inertial decoupler spring for use on fixed barrels. PEW Science postulates that a dedicated fixed mount would be more desirable for performance of the MOD9 FS on such weapons; however, that has not been evaluated.
The silencer is user-serviceable, which is a positive and necessary trait of pistol silencers in today’s market. As the primary baffle stack is aluminum, use of an ultrasonic cleaner is not recommended; the user is encouraged to contact the manufacturer for a recommended cleaning method and schedule, which will depend on the user’s firing schedule and ammunition use.
In this review, the MOD9 FS 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 perceived by both the shooter and bystanders.
