SSS.6.177 - Dead Air Mojave 9 and the HK P30L
/Dead Air Mojave 9 on the HK P30L Full-Size Semiautomatic Pistol
The Mojave 9 is designed by Dead Air Silencers. It is a 9mm centerfire pistol silencer, intended to suppress the 9x19mm cartridge from semiautomatic handguns and submachine guns. The Mojave 9 is a modular silencer with a 1.38-inch primary diameter, and its long configuration is 7.7 inches in length. In its short configuration, the silencer is 5.9 inches in length. These lengths include the internal inertial-decoupling piston possessing 1/2-28tpi or 13.5x1mm LH threading. Users should note that the Mojave 9 is only compatible with its own pistons; although SilencerCo/HUXWRX/Rugged pattern pistons may fit and function in the silencer, performance may be significantly degraded (see Research Caution, below). Direct-thread and 3-lug adapters are also available from Dead Air for the Mojave 9. The proximal and distal primary sections of the silencer are monolithically 3D-printed from 6AL-4V DMLS titanium. The end cap and piston retaining assembly are constructed from 7075 aluminum. The pistons are stainless steel. Tools may be used for full system disassembly, and the silencer is user-configurable for most operations by hand. With the piston and spring installed, the silencer weighs 9.7 ounces in the long configuration and 8.0 ounces in the short configuration, as tested. The Mojave 9 can be obtained from Silencer Shop.
! RESEARCH CAUTION !
As part of this internal research program, the PEW Science Laboratory conducted multiple instrumented blast tests with the Dead Air Mojave 9 silencer, in both its long and short configurations, on the HK P30L semiautomatic 9mm combat handgun with multiple inertial-decoupling pistons. Although many third-party pistons (e.g. those manufactured by SilencerCo, HUXWRX, Rugged Suppressors, etc) may fit and function in the silencer, PEW Science engineering analysis of the program test results indicates that the use of such non-Dead Air piston devices with the Mojave 9 silencer may result in significantly adverse increases to operator risk metrics. The Suppression Rating at both the muzzle and the shooter’s ear may be compromised by the use of such third-party pistons; the operator risk increase being the most pronounced. Suppression Ratings at the operator’s head may drop multiple categories. Physically, internal mechanical impact during system operation, likely outside the bounds of the intended design envelope, induces resonance and high frequency components in the signature and is the primary contributor to the increase in operator hazard. It is important to note that these adverse signature components occur in both different amplitude and time regimes than the primary blast loads, and quantifying such hazards without holistic engineering analysis of the full free field system signatures is not possible. For example, peak free field blast pressure may not be influenced by these piston variations. As always, the PEW Science Laboratory urges caution to users when attempting to interpret test results that do not contain accompanying engineering analysis. Future Member Research Supplements detailing these hazard increases will be published at a later date. All Member Research Supplements can be found here.
This Sound Signature Review contains test results and analysis for two silencer configurations in two tests, with the Dead Air-branded 13.5x1mm LH Mojave 9 piston (part number PB411). Test data was generated using the Dead Air Mojave 9 (Long and Short) 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 tests.
Section 6.177.1 contains the Mojave 9 test results and analysis in the long configuration.
Section 6.177.2 contains the Mojave 9 test results and analysis in the short configuration.
Section 6.177.3 contains Suppression Rating comparisons of the Mojave 9 with the Rugged Obsidian 9, CAT SC, SilencerCo Omega 9K, Inert Haze Ti-P, AAC Ti-RANT 9M-HD, AAC Ti-RANT 9M, AAC Ti-RANT 9, HUXWRX CA$H 9K, Resilient Suppressors RSP, CGS MOD9 FS, Rugged Obsidian 45, and SWR Trident-9 silencers, fired on the Heckler and Koch P30L.
Section 6.177.4 contains the review summary and PEW Science laboratory staff opinions.
Summary: When paired with the HK P30L full-size semiautomatic pistol and fired with Speer Lawman 147gr ammunition in its long configuration, the Dead Air Mojave 9 achieved a Suppression Rating™ of 58.3 in PEW Science testing. In its short configuration with the same host weapon and the same ammunition, the Mojave 9 achieved a Suppression Rating of 48.8. 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
6.177.1 Dead Air Mojave (Long) Sound Signature Test Results
A summary of the principal Silencer Sound Standard performance metrics of the Dead Air Mojave 9 in its long configuration 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. Dead Air Mojave 9 (Long Configuration) Sound Metric Summary
6.177.1.1 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 Dead Air Mojave 9 in its long configuration 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 6-shot test are shown in Figure 2a. In Figure 2b, a shorter timescale is shown comparing the impulse of Shots 1 through 3.
Fig 1a. Dead Air Mojave 9 (Long Configuration) subsonic 9x19mm HK P30L Semiautomatic Pistol Muzzle Sound Pressure Signature
Fig 1b. Dead Air Mojave 9 (Long Configuration) subsonic 9x19mm HK P30L Semiautomatic Pistol Sound Pressure Signature
Figure 2a. Dead Air Mojave 9 (Long Configuration) subsonic 9x19mm HK P30L Semiautomatic Pistol Muzzle Sound Impulse Signature
Figure 2b. Dead Air Mojave 9 (Long Configuration) subsonic 9x19mm HK P30L Semiautomatic Pistol Muzzle Sound Impulse Signature
The Dead Air Mojave 9 is the first DMLS (3D-printed) silencer in the Dead Air product line. Test reports for other Dead Air silencers evaluated in the Silencer Sound Standard research pedigree may be viewed here or found by sorting and filtering in the Rankings table, here. The Mojave 9 is a modular pistol silencer; it may be used in both its long or short configuration, similar to silencers like the Rugged Obsidian 9 (6.172), Obsidian 45 (6.7), the modern AAC Ti-RANT series (6.118), and the CAT SC (6.162). This section of the report addresses the long configuration performance. The short configuration performance is addressed in Section 6.177.2.
PEW Science Research Note 1: Both proximal (rear) and distal (forward) 3D-printed sections of the Mojave 9 are monolithic. Internally, the silencer uses the Dead Air Triskelion baffle geometry in both sections of the silencer. Conceptually, the Triskelion geometry is somewhat similar to a shape that may be generated by rotating a KAC stepped crimped-cone star-type baffle geometry about the bore axis, creating ancillary annular spiral vent passages. The three principal mechanisms of action in the Triskelion system are enhanced turbulence generation and heat transfer from maximized surface area and relatively high early-time flow rate through the annular vent area. In the first expansion chamber of the Mojave 9, the Triskelion geometry is tapered such that there is significant vent area around the outer circumference of the first reflector, which reduces early-time internal blast load impulse accumulation. The combination of this geometric feature and the aforementioned mechanisms results in significantly high sound suppression performance on a standard combat handgun, both in pure signature suppression and ejection port blast hazard reduction. In combination with its ancillary annular spiral vent passages that are fed by the early venting, all of these design features classify the Dead Air Mojave 9 as a hybrid design in the PEW Science research taxonomy.
The above measured signatures from this test of the long configuration of the Dead Air Mojave 9 display clear attributes of high performance, to include:
Relatively low free field blast pressure amplitude with ramped onset (Fig. 1a and 1b).
Significantly suppressed coupled jetting, even with higher distal flow rate (Fig. 1b).
Low rate of impulse accumulation that is very consistent even to maximum; known breech leak phenomena do not significantly influence this consistency (Fig. 2a and 2b).
In gross behavior, as well as in free field signature severity, the Dead Air Mojave 9 exhibits characteristics very similar to that of the Rugged Obsidian 9 (6.172), with several significant differences. The Mojave 9 exhibits more severe muzzle (bystander) FRP than the Obsidian 9. However, the Mojave 9 also exhibits a higher early time flow rate than the Obsidian 9, which directly contributes to significantly more favorable operator hazard reduction. Shooter’s ear signature analysis is provided in the full Member Version of this report.
PEW Science Research Note 2: As previously reported, bystanders adjacent to the weapon system with the Rugged Obsidian 9 may experience a signature that is over 80% more severe during the first shot than during subsequent shots. With the Dead Air Mojave 9, the muzzle first-round-pop (FRP) signature may be over 30% more severe than the muzzle FRP signature of the Obsidian 9, despite the two silencers having very similar muzzle Suppression Ratings. However, the Mojave 9 suppresses the muzzle signature more significantly through the shot string than does the Obsidian 9. These conclusions are derived from testing with full power subsonic ammunition, as is used in all of the displayed test data for 9mm pistol silencers evaluated in the Silencer Sound Standard. Use of underpowered ammunition may or may not result in user experience deviations from these conclusions.
The type of FRP suppression performance deficiency possessed by the Dead Air Mojave 9 is relatively commonplace among traditional centerfire handgun silencers, though there are exceptions. Notable cases of excellent FRP reduction include silencers such as the Resilient Suppressors RSP (6.87), the SWR Trident-9 (6.8), and the CAT SC (6.162). The aforementioned statement is based upon relative FRP performance, not absolute suppression. The reader is encouraged to examine Figure 9 in this report for absolute suppression metrics as well as the Rankings Section of the Standard. All three of the aforementioned silencers employ some method of ancillary flow path geometry, either in early time, late time, or both. This type of geometry may also contribute to FRP reduction, not only to high flow rate. The case study of the high back pressure Trident-9, which uses original Omega Baffles is a pertinent example of this. In the case of the Dead Air Mojave 9, its FRP suppression performance is reduced despite its annular vent paths. It is postulated that the relatively simplistic (but effective) method the Mojave 9 employs to increase early-time flow rate also may exacerbate FRP. Further research is needed.
PEW Science Research Note 3: FRP performance factors notwithstanding, the Dead Air Mojave 9 produces exceptionally high gross sound field suppression performance, on average. As discussed above, the Triskelion stepped and spiraled star-baffle geometry in the Mojave 9 may be considered a hybrid design in the PEW Science research taxonomy, in that it has features of traditional baffles with ancillary flow paths intended to reduce stagnation, increase early-time flow rate, reduce backpressure, and maintain distal momentum control. On closed-breech weapons, or weapons in which the chamber may be closed or extraction delayed by a relatively significant amount of time, high silencer flow rate is of less significance. However, almost all known traditional combat handguns using a modified Browning tilting-barrel action exhibit lock times unfavorable to significant backpressure generation. Back pressure in a silencer design is not blowback. Back pressure is caused by blast load impulse accumulation above given thresholds in various parts of the silencer, and therefore occurs in multiple time regimes. Blast load impulse accumulation is the result of not only pressure stagnation, but additive load reflections. Without clearing (venting), impulse will continue to accumulate during the time regimes of interest. Matching the time regime of clearing to the requisite weapon function sequence is paramount to the design process used by suppressed small arm weapon system developers (developers of the whole systems; silencers and hosts).
The Dead Air Mojave 9 joins the ranks of several centerfire pistol silencers which possesses designs that take into account the physical realities discussed above. Examples of silencers with low backpressure, intended to maximize shooter protection in the free field, include models such as the HUXWRX CASH 9K (6.96), the Resilient Suppressors RSP (6.97), and adjacently, the Inert Haze Ti-P (6.145). These three silencers do reduce operator hazard in the free field, particularly with respect to their low(er) muzzle (bystander) Suppression Ratings. The challenge for pistol silencer designers is to achieve a high degree of operator protection combined with a high degree of gross pressure field suppression. At the time of this article publication, the strongest performance potential demonstrating progress toward achieving that goal has been demonstrated by the aforementioned CAT SC. As with rifle suppression, the evolution of hybrid designs continues, and is expected to continue to increase performance dividends on semiautomatic host weapons. Over-bore (using a silencer with a bore aperture larger than required for cartridge-specific use) is seldom effective at reducing operator hazard on its own, both due to gross pressure field suppression compromise and early time blast load reflections that have little to do with bore size.
The Dead Air Mojave 9 is second only to the CAT SC in combining both excellent muzzle (bystander) hazard reduction with exceptional shooter’s ear (operator) hazard reduction. And, like the CAT SC, the Mojave 9 produces significant free field operator hazard reduction in both its long and short configurations. The short configuration test results and analysis of the Mojave 9 are presented in Section 6.177.2.
PEW Science Research Note 4: 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 5: Note that the muzzle Suppression Rating of the Dead Air Mojave 9 in its long configuration used on the full-size HK P30L semiautomatic handgun test host is 57.9 and the shooter’s-ear Suppression Rating is 45.5; 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 a semiautomatic host weapon. The signatures measured at the shooter’s ear are presented and examined below.
6.177.1.2 SOUND SIGNATURES AT SHOOTER’S EAR
Real sound pressure histories from the same 6-shot test of the Dead Air Mojave 9 in its long configuration 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. Dead Air Mojave 9 (Long Configuration) subsonic 9x19mm HK P30L Semiautomatic Pistol Ear Sound Pressure Signature
Figure 3b. Dead Air Mojave 9 (Long Configuration) subsonic 9x19mm HK P30L Semiautomatic Pistol Ear Sound Pressure Signature, Short Time Window
Figure 4a. Dead Air Mojave 9 (Long Configuration) subsonic 9x19mm HK P30L Semiautomatic Pistol Ear Sound Impulse Signature
Figure 4b. Dead Air Mojave 9 (Long Configuration) subsonic 9x19mm HK P30L Semiautomatic Pistol Ear Sound Impulse Signature Peaks
PEW Science Research Note 6: The Research Caution given at the beginning of this report is important for your understanding of the performance of the Dead Air Mojave 9 silencer system. Please note the oscillatory features in the pressure and impulse histories measured at the shooter’s ear at approximately 36 ms in the above data plots. These plots show the behavior of the factory Dead Air piston assembly. This is typical piston system mechanical shock, and very common in most centerfire suppressed 9mm combat handgun signatures. When using a third-party piston with the Dead Air Mojave 9, these mechanical shocks become significantly more severe, and they increase operator hazard. The Suppression Rating may drop two full categories due to the severe high frequency signature components induced by incorrect piston fielding. The user may not anticipate such performance changes, as third-party pistons both fit and function in the Dead Air Mojave 9. User caution is strongly advised. Please note that excessive mechanical shock may not present with higher peak blast pressure or peak blast impulse in test data. Hazards from this phenomenon manifest predominantly as frequency driven effects. Therefore, without comprehensive engineering analysis of the full time regime sound signatures, from before the initiation of combustion, until after full mechanical operation of the weapon system has ceased and the slide has returned to battery, unprocessed and unanalyzed test data may not display any signs of adverse hazards. The Suppression Rating calculations include frequency effects, as well as phase, amplitude, and duration components of the holistic signatures.
Other than in particular cases covered by the caution above, the signatures generated by this system at the operator’s head are much less severe than with a typical centerfire pistol silencer. The Dead Air Mojave 9 has a high enough early-time flow rate to significantly reduce the severity of ejection port blast to the weapon operator. Both muzzle blast and ejection port blast are significantly suppressed and the shooter’s ear Suppression Rating reflects that, at 45.5. This operator hazard reduction eclipses that of the Resilient Suppressors RSP, and the long configuration of the Dead Air Mojave 9 does this with significantly higher muzzle suppression performance. The CAT SC is the only silencer in the published research pedigree that outperforms the Mojave 9 in operator hazard reduction.
PEW Science Research Note 7: As discussed in previous test reports, there is a persistent observed phenomenon present in centerfire pistol silencer signatures when using the HK P30L standard test host. An early-time shock load propagates from the weapon breach prior to full propagation of the muzzle blast signature to the operator’s location. 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. Even with extremely high early-time flow rates, these short duration shock loads from the weapon breach still occur; regardless of long or short silencer configurations. As expected, they occur with the Dead Air Mojave 9 in both configurations. These shocks can be seen in Figure 3b at approximately 29.5 ms and the impulse generation is captured in Figure 4a. They occur, to some degree, in every shot other than Shot 2. While this test shows both higher prevalence to occur and higher impulse amplitude to be generated than with other silencers, no silencer tested has prevented the phenomena from occurring on this host weapon with full power test ammunition.
PEW Science Research Note 8: The reader is encouraged to compare the higher degree of mechanical shock in the Rugged Obsidian 9 test report (Fig. 3b, ~34.5 ms) with that of the data plots above. Ejection port blast and mechanical shock were elevated with the Obsidian 9 due to its design. The hybrid design of the Dead Air Mojave 9 addresses some of these shortcomings with its higher early-time flow rate.
PEW Science Research Note 9: Unlike to bystanders adjacent to the weapon muzzle, relative FRP severity differential at the operator’s head is postulated to minimally impact operator risk with the Mojave 9. This pressure field variance may be due to the relatively high flow rate of the Mojave 9; muzzle blast FRP is not shown to significantly propagate to the shooter in the same way it does to bystanders adjacent to the muzzle with this silencer on this particular weapon system.
The difference in performance, to the weapon operator, between the Dead Air Mojave 9 and other silencers, is significant in the free field. Outside of the free field, near reflecting surfaces, the performance differential may be more (or less) significant, as its holistic pressure field is highly suppressed, but ejection port blast loads can still reflect from surrounding surfaces.
The performance of the Dead Air Mojave 9 in its long configuration on a pistol, at the shooter’s ear, is driven by both muzzle signature and ejection port signature. When the distal (front) section of the silencer is removed, and the silencer is changed to its short configuration, the signature balance changes. Back pressure is somewhat reduced, but so is muzzle suppression performance, by a significant margin. This is demonstrated in the test summarized in the following section.
6.177.2 Dead Air Mojave 9 (Short) Sound Signature Test Results
A summary of the principal Silencer Sound Standard performance metrics of the Dead Air Mojave 9 in its short configuration 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 6.177.1, 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 2. Dead Air Mojave 9 (Short Configuration) Sound Metric Summary
6.177.2.1 SOUND SIGNATURES AT THE MUZZLE
Real sound pressure histories from a 5-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 Dead Air Mojave 9 in its short configuration are shown in Figure 5a. The sound signatures of Shot 1, Shot 2, and Shot 3 are shown in a shorter 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 and Shot 3.
Fig 5a. Dead Air Mojave 9 (Short Configuration) subsonic 9x19mm HK P30L Semiautomatic Pistol Muzzle Sound Pressure Signature
Fig 5b. Dead Air Mojave 9 (Short Configuration) subsonic 9x19mm HK P30L Semiautomatic Pistol Muzzle Sound Pressure Signature
Fig 6a. Dead Air Mojave 9 (Short Configuration) subsonic 9x19mm HK P30L Semiautomatic Pistol Muzzle Sound Impulse Signature
Fig 6b. Dead Air Mojave 9 (Short Configuration) subsonic 9x19mm HK P30L Semiautomatic Pistol Muzzle Sound Impulse Signature
The removal of the distal section of the Dead Air Mojave 9 to adapt it from its long to short configuration significantly changes its signature on the standard HK P30L test host. There are several notable signature differentials, including:
Higher gross free field blast pressure amplitude (Fig. 5a).
More expedient blowdown and subsequent higher amplitude and decoupled ground reflection (Fig. 5a).
Very high amplitude initial coupled jetting (Fig. 5b).
Immediate and severe primary jetting after (3) (Fig. 5b).
Corresponding early-time momentum accumulation in impulse space (~29.9 ms, Fig. 6b)
More expedient rise to maximum positive phase impulse throughout the entirety of primary distal flow (Fig. 6a).
The above differences are relatively typical when removing a substantial section from the distal end of a silencer. However, unlike as was the case in the examination of the short configuration of the Obsidian 9, FRP divergence is still significant with the short configuration of the Mojave 9. Somewhat similar behavior was noted in the evaluation of the short configuration of the AAC Ti-RANT 9M-HD (6.118) and short configuration of the Rugged Obsidian 45 (6.7). It is likely that the lack of divergence in the short Obsidian 9 test was due to the very severe blast propagation; that silencer configuration is not able to trap a significant amount of combustion byproducts for a long enough period of time to demonstrate adverse FRP behavior. The short configuration of the Mojave 9 exhibits muzzle suppression performance on par with most traditional short configuration pistol silencers.
The Dead Air Mojave 9 is 5.9 inches long in its short configuration. For context, the Obsidian 9 is 5.1 inches long in its short configuration, the SilencerCo Omega 9K (6.153) is 4.9 inches long, the HUXWRX CASH 9K (6.96) is 5.4 inches long, and the short configuration of the CAT SC (6.162) is 5.5 inches long. The short configuration of the Mojave 9 is the longest of the group, and matches the length of the short configuration of the AAC Ti-RANT 9 series, while matching the muzzle suppression performance of the shorter Omega 9K. The Mojave 9 significantly outperforms the higher back pressure Omega 9K in operator hazard reduction. All short models are outperformed by the short configuration of the CAT SC.
PEW Science Research Note 10: The muzzle Suppression Rating of the Dead Air Mojave 9, in the free field, changes from 57.9 to 39.2 when changing from its long to short configuration. This performance change, spanning two Suppression Rating Performance Categories, indicates that the hazard adjacent to the weapon system when the two different configurations of the silencer are used are significantly different. However, the operator hazard reduction with the short configuration of the Mojave 9 is very high. As discussed in detail in Section 6.177.2.2 of the full Member Report, the already high flow rate from the long configuration of the Mojave 9 is increased even further by removing the distal section. This change almost nullifies ancillary ejection port blast wave coalescence when compared to the use of other silencers on this host weapon. With a free field shooter’s ear Suppression Rating of 48.0, somewhat higher than the long configuration’s 45.5, the short configuration of the Dead Air Mojave 9 provides the third highest level of operator protection in the free field on this host weapon system in the Silencer Sound Standard, to date. Its performance is only eclipsed by the two configurations of the CAT SC. It is extremely important to note that the shooter’s ear Suppression Rating is calculated from free field blast overpressure data adjacent to the operator’s head. Environmental changes and deviations from free field conditions can, and most likely will, result in protection differentials that shift. Severe environmental differentials may provide severity with highly nonlinear characteristics and outcomes. PEW Science highly encourages examination of the full member version of this report for elaboration on these performance facts.
PEW Science Research Note 11: Both early time flow parameters (alpha) and gross flow parameters (Omega) influence weapon behavior. This report is an examination of the influence of changing Omega while keeping alpha constant; the change in configuration from long to short configuration of the Dead Air Mojave 9.
6.177.2.2 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 with the Dead Air Mojave 9 in its short configuration are shown in Figure 7a. A zoomed-in timescale is displayed in Figure 7b, in the region of peak sound pressure. The real sound impulse (momentum transfer potential) histories at the ear from the same 6-shot test are shown in Figure 8.
Figure 7a. Dead Air Mojave 9 (Short Configuration) subsonic 9x19mm HK P30L Semiautomatic Pistol Ear Sound Pressure Signature
Figure 7b. Dead Air Mojave 9 (Short Configuration) subsonic 9x19mm HK P30L Semiautomatic Pistol Ear Sound Pressure Signature
Figure 8a. Dead Air Mojave 9 (Short Configuration) subsonic 9x19mm HK P30L Semiautomatic Pistol Ear Sound Impulse Signature
Figure 8b. Dead Air Mojave 9 (Short Configuration) subsonic 9x19mm HK P30L Semiautomatic Pistol Ear Sound Impulse Signature
The shooter’s ear suppression performance from the Mojave 9 is significantly influenced by the increased gross flow rate (Omega decrease) from the removal of the distal section of the silencer. The duration of positive phase impulse is lower with the short configuration than with the long configuration (reference Fig 8a, above, and Fig 4a in the preceding test). However, the amplitude of the accumulation is significantly higher. This is due to muzzle blast. The net result is a higher level of protection for the operator, despite the higher blast impulse amplitude. Note that this conclusion is only valid in the free field, away from reflecting surfaces.
At these levels of performance, multiple signature parameters become important in differentiating competing models. The reader is encouraged to review the shooter’s ear test data with the short configuration of the CAT SC (6.162, Figure 8a) and compare it with Figure 8a, above. Note the differences in both amplitude and maximum impulse plateau. The short configuration of the CAT SC exhibits superior flow control, both in back pressure and in distal momentum propagation. The CAT SC is significantly more advanced than the Dead Air Mojave 9. That is not to say the Mojave 9 is a low performer; to the contrary, its operator hazard reduction in both configurations is very high. But, the repeated Triskelion baffle geometry is not staged like the SB-SHOCK technology in the CAT SC, and the simple initial expansion geometry of the Mojave 9 most likely does not lend itself to advanced FRP control.
PEW Science Research Note 12: The Suppression Rating at the shooter’s ear, on a centerfire pistol, when you change a silencer from its “long” configuration to its “short” configuration, may not appreciably change. However, when it does change, it is important to understand that the acute hazard to the operator is changing, and not necessarily the gross sound field overall “loudness.” The Dead Air Mojave 9 in its short configuration is likely considered “louder” than in its long configuration, but that is due to the gross decrease in muzzle Suppression Rating, not acute operator hazard. The detailed Suppression Ratings (muzzle and ear) quantify hearing damage risk to adjacent bystanders and the shooter, in the free field.
It is very important to note that what you, as a human, hear is a function of every pressure source propagating through the atmosphere that reaches your pressure sensors (your ears). In early time, the risk to your ear is highest. In late time, after the primary combustion events have vented, there are signature components that may propagate downrange, adjacent to your location, and even back toward you upon reflecting from objects such as tree lines, automobiles, or structures. Those late time signature components can give a subjective impression to the operator that may induce a perception of “loudness.” Loudness, as defined in the Silencer Sound Standard however, is objective hearing damage risk potential.
Factors that may increase the actual objective loudness (the risk to you, the operator) of using a system with a lower muzzle Suppression Rating despite the same or higher shooter’s ear Suppression Rating include shooting the suppressed weapon system:
Indoors.
In a vehicle or adjacent to a vehicle.
Adjacent to a building, berm, awning, or tree line.
This is the same phenomenon that presents when shooting a high flow rate centerfire rifle silencer on a reciprocating semiautomatic or automatic rifle. Reference the test report of the HUXWRX FLOW 556K (6.83) and FLOW 762 Ti (6.114), etc. Even if not indoors or adjacent to reflecting surfaces, late time signatures propagated from lower muzzle suppression rating systems will influence shooter perception in late time. This does not influence the shooter’s ear Suppression Rating because it does not increase the hearing damage risk potential to the shooter in the free field.
The following section presents overall comparisons of centerfire pistol silencer configurations on the HK P30L semiautomatic pistol.
6.177.3 Suppression Rating Comparison (Subsonic 9x19mm from the HK P30L)
Figure 9 presents a comparison of the PEW Science Suppression Ratings of the Dead Air Mojave 9 in both its long and short configurations with other silencers on the full-size HK P30L semiautomatic pistol using subsonic Speer Lawman 147gr 9mm ammunition.
Figure 9. Suppression Rating Comparisons of the Dead Air Mojave 9 in both long and short configurations with the Rugged Obsidian 9, CAT SC, SilencerCo Omega 9K, AAC Ti-RANT 9 Series, the HUXWRX CA$H 9K, 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
As previously discussed, the Dead Air Mojave 9 is second only to the CAT SC (6.162) in combining both excellent muzzle (bystander) hazard reduction with exceptional shooter’s ear (operator) hazard reduction. And, like the CAT SC, the Mojave 9 produces significant free field operator hazard reduction in both its long and short configurations. As summarized in Figure 9, above, the long configuration of the Mojave 9 produces higher operator hazard reduction than most 9mm pistol silencers in the free field, and is still able to maintain distal momentum control and protect bystanders on-par with that of traditional high performance silencers like the Rugged Obsidian 9 (6.172). The Triskelion hybrid technology in the Dead Air Mojave 9 shows significant performance efficacy in this combustion regime.
Mojave 9 Long Configuration Performance Notes: With regard to the performance of the long configuration of the Dead Air Mojave 9, as previously discussed, there are FRP factors of which the user should be aware. As previously reported, bystanders adjacent to the weapon system with the Rugged Obsidian 9 may experience a signature that is over 80% more severe during the first shot than during subsequent shots. With the Dead Air Mojave 9, the muzzle first-round-pop (FRP) signature may be over 30% more severe than the muzzle FRP signature of the Obsidian 9, despite the two silencers having very similar muzzle Suppression Ratings. However, the Mojave 9 suppresses the muzzle signature more significantly through the shot string than does the Obsidian 9. These conclusions are derived from testing with full power subsonic ammunition, as is used in all of the displayed test data for 9mm pistol silencers evaluated in the Silencer Sound Standard. Use of underpowered ammunition may or may not result in user experience deviations from these conclusions.
Mojave 9 Short Configuration Performance Notes: The Dead Air Mojave 9 is 5.9 inches long in its short configuration. For context, the Obsidian 9 is 5.1 inches long in its short configuration, the SilencerCo Omega 9K (6.153) is 4.9 inches long, the HUXWRX CASH 9K (6.96) is 5.4 inches long, and the short configuration of the CAT SC is 5.5 inches long. The short configuration of the Mojave 9 is the longest of the group, and matches the length of the short configuration of the AAC Ti-RANT series (6.118), while matching the muzzle suppression performance of the shorter Omega 9K. The Mojave 9 significantly outperforms the higher back pressure Omega 9K in operator hazard reduction. All short models are outperformed by the short configuration of the CAT SC.
PEW Science Research Note 13: Further examination of Figure 9 highlights an emerging trend in centerfire combat handgun silencer performance research. Hybrid designs, as classified in the PEW Science research taxonomy, are demonstrating the most significant performance potentials. While more primitive k-baffle, curved-cone baffle, and similar designs are capable of significant signature suppression performance, balanced protection for both the operator and bystanders is demonstrated to have the greatest chance of success with more modern solutions. The hybrid design taxonomy was recently listed and described in Research Note 5 of Report 6.175. PEW Science encourages the reader to review the requisite technologies, featured silencer models, and their performance potentials. Dead Air has now joined the group with the Triskelion baffle geometry. Further evaluations of the Triskelion system in additional combustion regimes are the subject of future PEW Science research.
The shooter’s ear Suppression Ratings of some silencers in Figure 9 are similar. This does not mean that the overall signature of the weapon system is identical. It means that the hearing damage risk to the shooter is almost identical, in the free field. Environmental changes and deviations from free field conditions can, and most likely will, result in protection differentials that shift. Severe environmental differentials may provide severity with highly nonlinear characteristics and outcomes. PEW Science highly encourages examination of the full member version of this report for elaboration on these performance facts.
PEW Science Research Note 14: Because the PEW Science Suppression Rating is a damage risk criterion (DRC), a lower Suppression Rating indicates a higher personnel hazard in the free field. Therefore, silencers with a lower Suppression Rating are postulated to be more hazardous to the unprotected ear than silencers with a higher Suppression Rating. To iterate, the Suppression Rating is a DRC - it is not a subjective quantity; it is an objective quantification of hearing damage risk potential.
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.
6.177.4 Review Summary: Dead Air Mojave 9 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 in its long configuration, the Dead Air Mojave 9 achieved a Suppression Rating™ of 58.3 in PEW Science testing. In its short configuration with the same host weapon and the same ammunition, the Dead Air Mojave 9 achieved a Suppression Rating of 48.8.
As with all weapon systems, the user is encouraged to examine both muzzle and ear Suppression Ratings.
PEW Science Laboratory Staff Opinion:
The Dead Air Mojave 9 is a modern lightweight and high performance modular centerfire pistol silencer intended for multiple uses. The versatility of its two length configurations and mount adaptability is notable. Perhaps even more notable is the high performance of its 3D-printed Triskelion baffle technology, which provides very high free field hazard reduction for both bystanders and the weapon operator in the long configuration; its high early-time flow rate is a significant performance factor. Classified as a hybrid design in the PEW Science research taxonomy, the specific implementation of the Triskelion geometry in the Dead Air Mojave 9 represents one of the highest performance examples of centerfire combat handgun suppression technology in recent history.
Both proximal (rear) and distal (forward) 3D-printed sections of the Mojave 9 are monolithic. Internally, the silencer uses the Dead Air Triskelion baffle geometry in both sections of the silencer. Conceptually, the Triskelion geometry is somewhat similar to a shape that may be generated by rotating a KAC stepped crimped-cone star-type baffle geometry about the bore axis, creating ancillary annular spiral vent passages. The three principal mechanisms of action in the Triskelion system are enhanced turbulence generation and heat transfer from maximized surface area and relatively high early-time flow rate through the annular vent area. In the first expansion chamber of the Mojave 9, the Triskelion geometry is tapered such that there is significant vent area around the outer circumference of the first reflector, which reduces early-time internal blast load impulse accumulation. The combination of this geometric feature and the aforementioned mechanisms results in significantly high sound suppression performance on a standard combat handgun, both in pure signature suppression and ejection port blast hazard reduction. In combination with its ancillary annular spiral vent passages that are fed by the early venting, all of these design features classify the Dead Air Mojave 9 as a hybrid design in the PEW Science research taxonomy.
With regard to the performance of the long configuration of the Dead Air Mojave 9, as previously discussed, there are FRP factors of which the user should be aware. As previously reported, bystanders adjacent to the weapon system with the Rugged Obsidian 9 may experience a signature that is over 80% more severe during the first shot than during subsequent shots. With the Dead Air Mojave 9, the muzzle first-round-pop (FRP) signature may be over 30% more severe than the muzzle FRP signature of the Obsidian 9, despite the two silencers having very similar muzzle Suppression Ratings. However, the Mojave 9 suppresses the muzzle signature more significantly through the shot string than does the Obsidian 9. These conclusions are derived from testing with full power subsonic ammunition, as is used in all of the displayed test data for 9mm pistol silencers evaluated in the Silencer Sound Standard. Use of underpowered ammunition may or may not result in user experience deviations from these conclusions.
The Dead Air Mojave 9 is 5.9 inches long in its short configuration. For context, the Obsidian 9 is 5.1 inches long in its short configuration, the SilencerCo Omega 9K is 4.9 inches long, the HUXWRX CASH 9K is 5.4 inches long, and the short configuration of the CAT SC is 5.5 inches long. The short configuration of the Mojave 9 is the longest of the group, and matches the length of the short configuration of the AAC Ti-RANT series, while matching the muzzle suppression performance of the shorter Omega 9K. The Mojave 9 significantly outperforms the higher back pressure Omega 9K in operator hazard reduction. All short models are outperformed by the short configuration of the CAT SC.
The Mojave 9 may be used with a variety of mounts; the user should contact Dead Air for guidance on varying mount use for their desired application. With regard to inertial-decoupling pistons for use on reciprocating semiautomatic pistols like the HK P30L used in this research program, PEW Science highly recommends that the user install a Dead Air-branded Mojave 9 piston (either 1/2-28tpi or 13.5x1mm LH, depending on user weapon need). Although SilencerCo, Rugged Suppressors, and HUXWRX pistons may fit and operate in the Dead Air Mojave 9, the use of third-party pistons may result in significantly increased personnel hazard. This is detailed in the Research Caution at the beginning of this report.
The Dead Air Mojave 9 is intended for use on both semiautomatic and automatic host weapons. While it is intended for pistol use, it is also intended to possess requisite durability for dual-use on pistol caliber carbines. Durability of the silencer during aggressive firing schedules on fixed barrel weapons has not been comprehensively 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, or the user can opt for a dedicated fixed mount.
In this review, the Dead Air Mojave 9 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.
