SSS.6.164 - Liberty Precision Machine Mach-L and the Q mini FIX 300 BLK Subsonic
/Liberty Precision Machine Mach-L on a Q mini FIX 300 BLK with 8-in Barrel
The Mach-L is designed and manufactured by Liberty Precision Machine. It is a 30 caliber centerfire rifle silencer, intended to suppress most cartridges with projectiles appropriately sized to travel through the bore. It has a 1.74-inch diameter and is 9.1 inches long with no mount. The total length with the included direct thread adapter is 9.28 inches. The user may choose to use third-party adapters compatible with the 1.375”-24tpi system. The silencer is tubeless and all welded components are titanium. The end cap of the Mach-L has a center section removeable aperture for future distal orifice changes. The silencer also uses a serial-ID ring on the rear portion of the silencer, under license. The silencer weighs 12.4 ounces, and the included titanium direct thread mount weighs 0.8 ounces, for a total system weight of 13.2 ounces, as tested. The Mach-L can be obtained from Liberty Precision Machine Dealers.
PEW Science is an independent private testing laboratory and also hosts the world’s only independent public 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 analysis production for this Sound Signature Review was funded in part by PEW Science Project PEW-LPM-087-001-24. Therefore, data pertaining to the Mach-L in this Sound Signature Review is published with the express written permission of Liberty Precision Machine, LLC.
This Sound Signature Review contains single-test results using the Mach-L with its direct thread mount on the Q mini FIX bolt action pistol, chambered in 300 BLK with an 8-inch barrel. Discreet Ballistics 190gr ammunition was used in the test.
Section 6.164.1 contains the Mach-L test results and analysis.
Section 6.164.2 contains Suppression Rating comparisons with selected .30 rifle silencers in the subsonic flow regime.
Section 6.164.3 contains the review summary and PEW Science laboratory staff technical opinions.
Summary: When paired with the Q mini FIX 8” 300 BLK and fired with Discreet Ballistics 190gr Subsonic Target ammunition, the Liberty Precision Machine Mach-L achieved a composite Suppression Rating™ of 72.8 in PEW Science testing.
The supersonic .308 performance of the Liberty Precision Machine Mach-L is detailed in Sound Signature Review 6.163, in which it achieved a composite Suppression Rating of 53.5.
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
6.164.1 Liberty Precision Machine Mach-L Sound Signature Test Results
A summary of the principal Silencer Sound Standard performance metrics of the Mach-L 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. Liberty Precision Machine Mach-L Sound Metric Summary
6.164.1.1 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 laboratory sound signature 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 laboratory testing; the recognized industry leader in silencer sound research. For more information, please consult the Silencer Sound Standard.
The primary sound signature pressure histories for all 5 shots are shown in Figure 1a. A zoomed-in timescale displays the region of peak sound pressure in Figure 1b, for the first three shots. 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 to that of Shot 3 and Shot 5.
Fig 1a. Liberty Precision Machine Mach-L Bolt Action 300 BLK Muzzle Sound Pressure Signature
Fig 1b. Liberty Precision Machine Mach-L Bolt Action 300 BLK Muzzle Sound Pressure Signature, Short Time Window
Figure 2a. Liberty Precision Machine Mach-L Bolt Action 300 BLK Muzzle Sound Impulse Signature
Figure 2b. Liberty Precision Machine Mach-L Bolt Action 300 BLK Muzzle Sound Impulse Signature
The Liberty Precision Machine Mach-L has also been evaluated in the 7.62x51mm supersonic ammunition combustion regime (6.164). Some of the same design attributes enabling high performance with high pressure long duration combustion also pay dividends with lower pressure, shorter duration combustion. The subsonic 300 BLK performance of the Mach-L is significantly high. Several physical behaviors of note are observed in the above measured test data:
Relatively low amplitude overpressure signature with long duration blowdown (Fig. 1a).
Typical low amplitude internal combustion signature (Fig. 1b).
Subsequent to (2), coupled higher amplitude combustion signature with precursor flow (Fig. 1b, 30.2 ms).
Relatively significant FRP divergence with early onset in both pressure space and impulse space (Fig. 2b), along with significant initial FRP rarefaction.
Latent shot impulse increase (Fig. 2b), similar to phenomenon measured in 7.62 NATO testing (ref. 6.163, Fig. 2b).
Despite the extended duration in (1), the coupled phenomenon in (3), significant FRP divergence in (4), and latent blast impulse accumulation increase in (5), the Liberty Precision Machine Mach-L still achieves the highest muzzle signature severity reduction in the currently published research pedigree. The Mach-L achieves an unprecedented muzzle Suppression Rating of 71.3. This demonstrates significant pressure field suppression adjacent to the weapon system, in the free field.
PEW Science Research Note 1: It is fortuitous that the staged design of the Mach-L, previously highlighted in its 7.62 NATO testing, behaves as a “gas trap.“ This type of behavior, when moving from supersonic high pressure ammunition suppression, often translates well to subsonic low pressure ammunition suppression. When transitioning from the later to the former, less robust performance observations often occur. For example, the Q Full Nelson (6.99) demonstrates significantly high subsonic suppression performance. However, its Cherry Bomb-mounted sister silencer, the Q Thunder Chicken (6.20), demonstrates less than optimal supersonic suppression performance. This is due to the distinct lack of pressure stagnation relief in the subsonic-centric Q rifle silencer designs. Typically, high performance supersonic silencers also perform well with subsonic ammunition. A notable exception is Flow-Through designs from HUXWRX (OSS). The high degree of subsonic performance loss in those systems is highlighted in the evaluation of the HX-QD 762 (6.45). Combustion regime pressure and duration-dependent performance transitions between Q rifle silencers and HUXWRX rifle silencers are diametrically opposed.
PEW Science Research Note 2: To iterate, the Liberty Precision Machine Mach-L exhibits extremely high performance on this weapon system. Nonetheless, there are other phenomena that translate from its high pressure behavior to its low pressure suppression performance that are somewhat less than optimal. The FRP control from the system is one, and is of relatively little significance. The more significant performance trait is the early-time internal combustion signature (ref. Research Note 2, 6.163). When relative early-time pressure amplitude is higher, this type of behavior is of less consequence. When moving to the upper performance echelons of subsonic 300 BLK bolt-action suppression, such behavior more significantly contributes to the pressure field. It is not the bystander that is subjected to this adverse performance differential; it is the operator. This is one factor that contributes to the low(er) shooter’s ear Suppression Rating of the Mach-L on this host. This factor is further discussed in Section 6.164.1.2 of the Member Version of this review.
Another adverse performance factor that is carried over from the 7.62 NATO examination of the Mach-L is the latent impulse increase (5, above). Serendipitously, the overall muzzle signature severity from the Mach-L on this platform is so low, that its contribution to bystander risk is minimal. And for the operator, the aforementioned phenomena is of more significance.
PEW Science Research Note 3: The same staged array that provides exceptional 7.62 NATO performance with the Mach-L is somewhat inefficient with taming FRP combustion; not because of the holistic design, but because the level of suppression is so high, minute differences in severity are highlighted more than typical. Again, the relative FRP severity to bystanders with the Mach-L, on this weapon system, is not significant.
PEW Science Research Note 4: The performance of the Liberty Precision Machine Mach-L with subsonic 300 BLK is relatively close to that of both the legacy Q Full Nelson (6.99) and the CGS Hyperion (6.71). These silencers have high performance with combined low FRP severity. Moving to silencers like the Otter Creek Labs Hydrogen-L (6.94) and Resilient Suppressors Jolene (6.138) results in more significant FRP in this regime, to bystanders.
With subsonic 300 BLK from an 8-inch barrel, the Liberty Precision Machine Mach-L produces a less severe signature to bystanders than many silencers on this host weapon. Direct comparisons with other silencers are provided in Section 6.164.2.
6.164.1.2 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 at the ear for all 5 shots are shown in Figure 3. 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. The real sound impulse (momentum transfer potential) histories at the ear from the same 5-shot test are shown in Figure 4. Full and short timescales are shown.
Figure 3a. Liberty Precision Machine Mach-L Bolt Action 300 BLK Ear Sound Pressure Signature
Figure 3b. Liberty Precision Machine Mach-L Bolt Action 300 BLK Ear Sound Pressure Signature, Short Time Window
Figure 4a. Liberty Precision Machine Mach-L Bolt Action 300 BLK Ear Sound Impulse Signature
Figure 4b. Liberty Precision Machine Mach-L Bolt Action 300 BLK Ear Sound Impulse Signature
The signatures measured at the operator’s head with the Mach-L on this platform display relatively unique behavior. Although they are of very low amplitude and the shooter’s ear Suppression Rating is an extremely high 66.0, there are some signature features that result in the severity being somewhat higher than typical for its muzzle Suppression Rating on the platform. One phenomenon is the aforementioned coupled internal combustion signature which forces early rarefaction (Fig. 3b, 28 ms). These early events, which are physically produced from blast wave expansion into the titanium body of the Mach-L, continue to drive down positive phase impulse until first muzzle jetting forces an abrupt transition to positive phase (Fig. 4b). Phase change smoothness in momentum transfer potential can influence severity at these high performance levels.
PEW Science Research Note 5: The same behavior that was noted in the 7.62 NATO testing of the silencer is very clearly illustrated in Figure 3b, in which the FRP divergence occurs not only during initial coupled combustion and precursor jetting, but during primary flow after jetting delay (Fig. 3b, ~32 ms). This ramped onset gives way to latent accumulation. There are two phases of gas dump with the Mach-L; the initial jet and primary flow. Regardless of combustion regime (7.62 NATO or subsonic 300 BLK), the silencer’s behavior is mirrored in a gross sense.
PEW Science Research Note 6: The FRP, to the shooter, is more severe with the Mach-L on this weapon system than it is to bystanders. Due to a larger proportion of this FRP event being composed of early-time combustion, such an FRP signature may present to the operator as “a more intense or louder metallic sound” or other mechanical/metallic type signature. When firing this system, it is postulated that the operator will notice more of the weapon system’s material-induced noise than the suppressed gunshot, until much later time.
PEW Science Research Note 7: With further regard to later time blast load signature propagation and severity, it is important to note that because the muzzle Suppression Rating of the Mach-L on this weapon system is so high, many shooting environments outside the free field may present sound fields to the operator that demonstrate a higher degree of operator hazard reduction than other silencers. Environment will strongly influence operator perception with the Mach-L on this weapon system.
The signature to the shooter with the Mach-L, in the free field, is on par with other high performance subsonic 300 BLK silencers like the Hydrogen-L, Hyperion, and CAT ODB.
Comparisons with other silencers in the subsonic flow regime are shown in Section 6.164.2, below.
6.164.2 Suppression Rating Comparison - Subsonic 300 BLK
The Liberty Precision Machine Mach-L was developed with a focus on high pressure sound signature reduction (PEW Science Suppression Rating), without regard to gross flow rate. As previously discussed, its subsonic sound signature suppression performance is very high. Figure 6 shows a performance comparison of many 30 caliber rifle silencer configurations tested with the subsonic 300 BLK cartridge shown in public PEW Science testing, to date. Unsuppressed and suppressed Suppression Ratings are shown for both the shooter and bystanders. The silencers in the figure are shown in no particular order.
Figure 6. Suppression Rating Comparisons Of .30 Rifle Silencers Using PEW-SOFT 300 BLK Subsonic Test Data
The performance of the Liberty Precision Machine Mach-L with subsonic 300 BLK is relatively close to that of both the legacy Q Full Nelson (6.99) and the CGS Hyperion (6.71). These silencers have high performance with combined low FRP severity. Moving to silencers like the Otter Creek Labs Hydrogen-L (6.94) and Resilient Suppressors Jolene (6.138) results in more significant FRP in this regime, to bystanders.
It is interesting to note that the shooter’s ear Suppression Rating of the Mach-L is very close to that of the Combat Application Technologies CAT/ODB/A1/718 (6.122). The size envelopes, flow rates, technologies, and suppression methodologies from the two silencers are radically different. A much more restrictive silencer, the Mach-L produces a much less severe pressure field adjacent to the muzzle. But, to the operator in the free field, risk is comparable. Environment, signature features, and host, all significantly influence gross severity of a suppressed small arm weapon system.
Despite several of the performance observations highlighted at the beginning of this report, the Liberty Precision Machine Mach-L still achieves the highest muzzle signature severity reduction in the currently published research pedigree. The Mach-L achieves an unprecedented muzzle Suppression Rating of 71.3. This demonstrates significant pressure field suppression adjacent to the weapon system, in the free field.
PEW Science Research Note 8: As discussed in the 7.62 NATO evaluation of the Mach-L, the upper echelons of 30 caliber suppression performance continue to be stretched (ref. Research Note 3, 6.163). It is again postulated that hybrid designs, staged designs, and other technological advancements will continue to emerge and define the state-of-the-art. High pressure stagnation relief, repeated axially through long(er) centerfire rifle silencers, is no longer sufficient to push the performance envelope in the supersonic ammunition combustion regime, but continues to demonstrate high performance with shorter duration lower pressure systems (subsonic 300 BLK). This is demonstrated by the Full Nelson, Hydrogen-L, Jolene, and others. Primitive and small silencers like the Energetic Armament VOX-S (6.25) will continue to be eclipsed in performance, in this combustion regime. For compact designs to excel in performance with subsonic 300BLK, they must employ much more advanced technology.
With further FRP control, heavier construction, and different gas re-routing in certain stages, the Liberty Precision Machine Mach-L would most likely meet or exceed the shooter’s ear hazard reduction of the Full Nelson. Nonetheless, as it stands, the performance of the Mach-L is extremely notable with both subsonic 300 BLK and 7.62 NATO. This is an impossibility for the legacy Q rifle silencer technology.
The difference in sound signature suppression performance from silencers in the subsonic 300 BLK suppression regime can be extremely significant. The user is encouraged to be mindful of the degree to which sound signature suppression, and resulting personnel hazards, can vary across designs. Small arm weapon system suppression performance is a spectrum. The PEW Science Suppression Rating and the Silencer Sound Standard help quantify this spectrum for end users and industry, objectively.
6.164.3 Review Summary: Liberty Precision Machine Mach-L on a Q mini FIX 300 BLK with 8-in Barrel
When paired with the Q mini FIX 8” 300 BLK and fired with Discreet Ballistics 190gr Subsonic Target ammunition, the Liberty Precision Machine Mach-L achieved a composite Suppression Rating™ of 72.8 in PEW Science testing.
The supersonic .308 performance of the Liberty Precision Machine Mach-L is detailed in Sound Signature Review 6.163, in which it achieved a composite Suppression Rating of 53.5.
As with all weapon systems, the user is encouraged to examine both muzzle and ear Suppression Ratings.
PEW Science Laboratory Staff Opinion:
The Liberty Precision Machine Mach-L is a lightweight full-size 30 caliber rifle silencer that demonstrates extremely high performance in multiple combustion regimes. For a traditionally-manufactured system, the performance of the Mach-L is an example of the upper echelon of staged design efficiency and consistency. The technology in the titanium Mach-L is also implemented in the stainless steel Anthem 2 series; the Mach series may be considered identical to the Anthem 2 series, other than construction material. Both the Mach and Anthem 2 series possesses user-adaptable mounting systems.
Significant and efficient pressure stagnation relief with accompanying downstream restriction is the primary combination of gross performance attributes in the Mach-L that produce the noted efficiency in the measured pressure field with 7.62 NATO cartridges. Some of the same design attributes enabling high performance with high pressure long duration combustion also pay dividends with lower pressure, shorter duration combustion. The subsonic 300 BLK performance of the Mach-L is significantly high.
The performance of the Liberty Precision Machine Mach-L with subsonic 300 BLK is relatively close to that of both the legacy Q Full Nelson and the CGS Hyperion. These silencers have high performance with combined low FRP severity. Moving to silencers like the Otter Creek Labs Hydrogen-L and Resilient Suppressors Jolene results in more significant FRP in this regime, to bystanders.
It is interesting to note that the shooter’s ear Suppression Rating of the Mach-L is very close to that of the Combat Application Technologies CAT/ODB/A1/718. The size envelopes, flow rates, technologies, and suppression methodologies from the two silencers are radically different. A much more restrictive silencer, the Mach-L produces a much less severe pressure field adjacent to the muzzle. But, to the operator in the free field, risk is comparable. Environment, signature features, and host, all significantly influence gross severity of a suppressed small arm weapon system.
The rear mount threading of the Liberty Precision Machine Mach-L is 1.375”-24tpi; relatively common in many modern rifle silencers. As a result of this common modular interface, a plethora of mounting systems may be used. The performance of the Mach-L may be influenced by mounting system choice.
The Mach-L is not “full-auto-rated;” it is a bolt-gun silencer intended for relatively short duration firing schedules. The user is encouraged to contact the manufacturer for barrel length and firing schedule restrictions. Note again that the Liberty Precision Machine Anthem 2 series mirrors the technology in the Mach series, with stainless steel construction instead of titanium.
In this review, the Mach-L performance metrics depend upon suppressing a subsonic intermediate rifle cartridge. 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 rifle cartridge suppression claims. The gas volume and combustion products created by firing a subsonic intermediate rifle cartridge such as 300 BLK are still significant; the measured pressure and impulse magnitudes, and their durations, illustrate this fact.
The hearing damage potential of subsonic rifle 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.
