SSS.6.163 - Liberty Precision Machine Mach-L and the Savage Model 10 PC .308 (Free Version)
/Liberty Precision Machine Mach-L on a Savage Model 10 .308 with 20-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 review contains single test results using the Liberty Precision Machine Mach-L with the direct-thread mount on the Savage Model 10 Precision Carbine rifle, chambered in .308WIN with a 20-inch barrel. Federal XM80 149gr ammunition was used in the tests.
Section 6.163.1 contains the Liberty Precision Machine Mach-L test results and analysis.
Section 6.163.2 contains back pressure and Suppression Rating comparisons with selected .30 rifle silencers possessing a PEW Science Back Pressure Metric, Ω [Pa-1] in Omega Zones 6 and above. An updated Ω metric chart for the full suite of publicly evaluated .30 rifle silencers is also provided in this section. Further information about the Ω metric and Omega Zones can be obtained in PEW Science Research Supplement 6.40 (Public Article).
- Section 6.163.3 contains the review summary and PEW Science laboratory staff technical opinions.
Summary: When paired with the Savage M10 20” .308 and fired with Federal XM80, the Liberty Precision Machine Mach-L with the direct-thread mount achieved a Suppression Rating™ of 53.5 in PEW Science testing.
The subsonic 300 BLK performance of the Liberty Precision Machine Mach-L is detailed in Sound Signature Review 6.164, in which it achieved a composite Suppression Rating of 72.8.
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
6.163.1 Liberty Precision Machine Mach-L Sound Signature Test Results
A summary of the principal Silencer Sound Standard performance metrics of the Liberty Precision Machine 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. The data acquired 0.15 m (6 in) right of the shooter’s ear is only available to membership supporters of PEW Science and the Silencer Sound Standard. You can support public PEW Science testing, research, and development with a membership, here. State-of-the-art public firearm sound signature testing and research conducted by PEW Science is supported by readers like you.
Table 1. Liberty Precision Machine Mach-L Sound Metric Summary
6.163.1.1 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.
The primary sound signature pressure histories for all 5 shots with the Mach-L are shown in Figure 1a. The sound signatures of Shot 1, Shot 2, and Shot 3 are shown in Figure 1b, in early time. The real sound impulse (momentum transfer potential) histories from the same 5-shot test are shown in Figure 2a. In Figure 2b, a shorter timescale is shown comparing the impulse of Shot 1 to that of Shot 3 and Shot 5.
Fig 1a. Liberty Precision Machine Mach-L Bolt Action Rifle Muzzle Sound Pressure Signature
Fig 1b. Liberty Precision Machine Mach-L Bolt Action Rifle Muzzle Sound Pressure Signature, Short Time Window
Figure 2a. Liberty Precision Machine Mach-L Bolt Action Rifle Muzzle Sound Impulse Signature
Figure 2b. Liberty Precision Machine Mach-L Bolt Action Rifle Muzzle Sound Impulse Signature, Short Time Window
The Mach series of silencers utilizes an updated version of the technology implemented in the Anthem series, previously characterized in the test report of the Liberty Precision Machine Anthem-S (6.79). The Mach-L examined in this test report is the full-size iteration of the series, sharing design attributes with the Anthem L2. For all intents and purposes, the Mach series silencers are Anthem 2 series silencers manufactured from titanium instead of stainless steel. Therefore, performance of the Anthem L2 is postulated to be similar to that of the Mach-L in this report.
Evaluation of the Mach-L showcases how the performance of the updated Anthem series design behaves with further distal flow restriction. There are several notable features in the above measured test data that illustrate this behavior, including:
Significant decoupling between consistent initial coupled jetting and primary blowdown (Fig. 1a).
Relatively long duration primary blowdown (Fig. 1b).
Relatively significant internal combustion signature prior to initial coupled jetting (Fig. 1b).
Significantly delayed positive phase impulse accumulation, in conjunction with (1), (Fig. 2a).
Relatively early onset FRP divergence with accelerated accumulation from latent shots in the string (Fig. 2b).
The Mach-L possesses significant distal flow control, which through significant time delay produces one of the least severe signatures measured at the muzzle of any silencer evaluated in the research pedigree. Therefore, the Liberty Precision Mach-L represents one of the most advanced traditionally (subtractive) manufactured silencers tested, to date.
PEW Science Research Note 1: 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 displayed above. Second only to the PTR VENT 1 (6.160) in gross muzzle signature severity reduction, the Liberty Precision Mach-L achieves its performance through entirely different physical mechanisms. Whereas the Purposely Induced Porosity (PIP) technology in the VENT 1 immediately throttles pressure amplitude and facilitates an expedient blowdown duration, the Mach-L uses the traditional technique of immediate pressure stall with subsequent blowdown delay. Although the net result from both technologies is significant suppression, the methods by which the suppressions are achieved create two distinctly different pressure fields:
The PTR VENT 1 reduces primary flow severity immediately and expediently.
The Liberty Precision Mach-L delays both the onset and blowdown of primary flow.
The two silencers are significantly different; this comparison of the technologies in the two silencers, and the resulting gross signature suppression performances, highlights the vastness of rifle silencer innovation at the upper echelons of performance.
PEW Science Research Note 2: In addition to gross signature and distal flow differentials, PEW Science postulates there are significant early-time flow differences between the Mach-L and the aforementioned PTR VENT 1. The blast chamber of the Mach-L does possess venting which helps to alleviate adverse impulse accumulation in close proximity to the first reflector. However, there is less vent area and continued flow diversion than present in the VENT 1. This is expected, due to the differences in the technologies. One consequence of the blast chamber geometry, coupled with the material and mass distribution of the Mach-L, is internal combustion signature. As noted in (3) above, the early time pressure field from the Mach-L is consistent but relatively high amplitude. This is of some consequence when examining the severity on the system tested herein; however, such signature components can contribute to an even greater portion of system severity when the combustion regime is changed. Subsonic 300 BLK combustion, for example, produces lower signature severity amplitudes which may allow these type of phenomenon to be highlighted when in close proximity to the system (e.g. at the operator’s location). Research into these factors and their effects on field severity is ongoing.
PEW Science Research Note 3: The Liberty Precision Mach-L exemplifies the performance potential of a highly efficient design philosophy utilizing traditional methods with the addition of purposeful flow staging. An excellent contrasting comparison with the Mach-L is the Dead Air Nomad-L (6.55). The Mach-L is longer than the Nomad-L, but its stagnation relief, pressure control, and consistency is significantly more robust. The Mach-L vents gas faster, despite being longer and quieter. The Nomad-L borrows some design cues from the CGS Hyperion (6.27), but the implementation is simply repeated baffle-to-baffle. The Mach-L, like the Hyperion, uses staged design, implementing geometric changes as the pressure state changes toward the distal end.
Another example of staged design is presented in another completely different design philosophy; SNIPER2 technology implemented in the CAT JL (6.147). The CAT JL is identical in length to the Nomad-L, and its staged design creates a less severe gross sound field, though with significantly higher distal flow creating more severity immediately adjacent to the muzzle.
As the upper echelons of 7.62 NATO suppression performance continue to be stretched, it is 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. Analysis of the test data in the aforementioned PTR, CGS, and CAT test reports, along with the Liberty Precision Machine data herein, strongly supports this conclusion. Silencers like the Nomad-L, Resilient Suppressors Jolene (6.137), Diligent Defense Enticer-L (6.67), and Otter Creek Labs Hydrogen-L (6.81) demonstrate high performance, and they also demonstrate technological performance plateaus. The Liberty Precision Machine Mach-L is a more advanced silencer, and its performance demonstrates this fact.
PEW Science Research Note 4: There is a phenomenon demonstrated in the Mach-L test data that occurs in both this report of its 7.62 NATO suppression, as well as in the test report of its subsonic 300 BLK suppression (6.164). As noted in (5) above, after Shot 3, blast load impulse accumulation is shown to increase. This increase in momentum transfer potential begins to meet and exceed that measured during FRP. PEW Science postulates that this is a heat-soak driven phenomenon. The type of design and manufacturing of the Mach-L, and the mirroring of the phenomenon in the subsonic ammunition combustion regime, supports this hypothesis. Adverse severity results from this phenomenon are somewhat negligible, but they are measurable and these factors do become more significant at these levels of performance with regard to comparisons. Nonetheless, the relative FRP severity from the Mach-L, on this weapon system, is nominal. It is postulated that bystanders will be subjected to only minimal severity differential during the first shot. As the system continues to be fired, severity will drop, and is then postulated to increase as shown. Again, this behavior is reasonable to expect from this type of technology and manufacturing.
As typically indicated, first-round sound signatures always differ from subsequent shots, as the atmosphere within the silencer changes. The FRP phenomenon cannot always be shown by viewing only the peak sound pressure. This is one of the reasons why The Silencer Sound Standard requires examining multiple sound signature metrics. Ammunition consistency can play a role in the determination of FRP, however, the close examination of measured pressure and impulse waveforms typically excludes ammunition from the possible factors influencing true FRP, due to the relative consistency of most high quality factory ammunition.
PEW Science has made a concerted effort to characterize the FRP phenomenon with true physiological human inner-ear response analyses. Additional PEW Science Member Research Supplements containing this information are released periodically. Shooter’s ear hazard analysis and phenomenology examination is provided in the Member Version of this report.
6.163.2 Relative Suppression Rating and Back Pressure Comparisons (.30 Rifle Silencers)
The Liberty Precision Machine Mach-L suppressor is intended to offer significant sound signature suppression across the pressure field, without regard to system backpressure. PEW Science has developed an empirical relation to quantify the back pressure (flow restriction) of silencers. Figure 5 and Figure 6 show supersonic suppression and back pressure comparisons between selected 7.62mm (30 caliber) rifle silencers shown in public PEW Science Sound Signature Reviews, as of the date of this review publication. The results shown in Figure 5 and Figure 6 are calculated from real test data acquired with PEW-SOFT. Please note the following:
The PEW Science Back Pressure Metric, Ω [Pa-1], may be generated for any silencer and suppressed weapon system using any suitable raw external overpressure signature data acquired 1.0 m left of the silencer end cap. PEW Science highly recommends data acquisition in accordance with The Silencer Sound Standard.
Omega Zones are presented in Table 2, below, which are intended to provide guidance to weapons developers, silencer designers, and end-users, with regard to flow restriction characteristics of different silencer designs. It is very important to note that silencers possessing a relatively high Ω can still provide functional use on weapon systems. Some weapon systems are more sensitive to Ω than others.
It is important to note that a silencer’s Omega Zone can shift when using a mounting scheme that differs from that used in the testing referenced in the published PEW Science Sound Signature Reviews. This phenomenon occurs due to some silencer mounting schemes significantly influencing flow restriction with some silencer designs.
The theoretical lower limit of flow restriction, or so-called "zero back pressure" would be represented by the unsupressed state, Ω = 0 [Pa-1].
PEW Science acknowledges that other dynamic events occur within a suppressed weapon system that can also influence weapon function. Therefore, PEW Science acknowledges that Ω is not the sole parameter one must consider for total supppressed weapon system operation. However, PEW Science postulates that the Ω metric influence can be significant. Note that weapon system influence is also a function of early-time wave propagation factors which may be measured inside the system, in close proximity to the muzzle orifice. These factors include the so-called PEW Science Alpha parameter; a subject of internal research.
The Back Pressure Metric relations are most easily viewed on a logarithmic scale (See Figure 6).
Figure 5. Omega Back Pressure Metric And Suppression Rating Comparisons Of .308 Rifle Silencers Using PEW-SOFT Data and Analysis
As stated above, the PEW Science Back Pressure Metric is most easily viewed on a logarithmic scale. The metric is nonlinear; the shape of the trend in the data presented in Figure 6, below, illustrates the potential thresholds of extreme flow rate (approaching the unsuppressed state) and extreme flow restriction (approaching the trapping of the maximum amount of combustion byproducts in a system).
Figure 6. Omega Back Pressure Metric Comparisons Of .308 Rifle Silencers Using PEW-SOFT Data and Analysis
Omega characterizes silencer back pressure. It is important to note that back pressure is not blow back. The back pressure of a silencer is the flow restriction it introduces in a suppressed weapon system. The blow back phenomenon that can occur during the use of a suppressed weapon system is caused by the reciprocating system actuating too early relative to overpressure decay within the weapon system, resulting in exposure of excessive internal system overpressure to atmosphere. Some weapons may be tuned to function well with silencers in a high Omega Zone. Some weapons may require low-Omega silencers due to constraints in their operating system(s). Omega metric technical details can be found in PEW Science Public Research Supplement 6.40.
Table 2. PEW Science Back Pressure Metric Omega Zones And Suppressed Weapon System Functional Descriptions
As stated above, weapon system influence is a function of both Ω and early-time wave propagation factors which may be measured inside the system, in close proximity to the muzzle orifice. These factors include the so-called PEW Science Alpha parameter; a subject of internal research. The Liberty Precision Machine Mach-L possesses some blast chamber venting which most likely influences both early time shock reflections near the muzzle and late time momentum accumulation. Due to the overall design of the Mach-L, its Omega Metric is relatively high. As previously discussed in Research Note 1, the methods by which the Mach-L achieve its high suppression performance dictate this behavior.
The suppression performance of the Mach-L on this platform, holistically, is best compared with the aforementioned PTR VENT 1 (6.160), CAT JL (6.147), CGS Hyperion (6.27), Dead Air Nomad-L (6.55), and Diligent Defense Enticer-L (6.67), as well as with the Otter Creek Labs Hydrogen-L (6.81) and Resilient Suppressors Jolene (6.137). It should be noted that all of the aforementioned silencers exhibit extremely high suppression performance in this combustion regime. These silencers objectively outclass most 30 caliber rifle silencers evaluated on this host weapon system by PEW Science, to date. However, as previously discussed in Research Note 3, the Nomad-L, Enticer-L, Hydrogen-L, and Jolene demonstrating both high performance and areas of potential improvement, are not mutually exclusive. High pressure stagnation relief, repeated axially through long(er) centerfire rifle silencers, is no longer sufficient to push the performance envelope. Staged designs are now demonstrated as one method to overcome technological performance plateaus. With these design advancements, the Liberty Precision Machine Mach-L is a more advanced traditionally manufactured silencer, and its performance demonstrates this fact.
PEW Science urges the reader not to misconstrue a low Omega metric with the mirroring of unsuppressed weapon function, nor a high Omega Metric with absolute use prohibition on semi-automatic systems. Each weapon system may experience varying sensitivity to different Omega Zones and users may exhibit varying preference for weapon system function and operability. The Zones are provided by PEW Science to assist the reader with determination of postulated applicability of silencer types, as some users may only have experience with certain silencers. The Omega Metric is one performance indicator; it allows overall flow rate phenomena to be categorized independently from sound signature suppression performance. Note that weapon system influence is also a function of early-time wave propagation factors which may be measured inside the system, in close proximity to the muzzle orifice.
PEW Science Research Note 8: The blast chamber venting of the Mach-L may provide appropriate use condition on limited reciprocating systems, despite its significantly long blowdown duration. However, the applicability of the Mach-L on such systems has not been evaluated by PEW Science. The user is encouraged to contact Liberty Precision Machine for additional information on that type of system applicability.
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.
6.163.3 Review Summary: Liberty Precision Machine Mach-L on a Savage Model 10 .308 with 20-in Barrel
When paired with the Savage M10 20” .308 and fired with Federal XM80, the Liberty Precision Machine Mach-L with the direct-thread mount achieved a Suppression Rating™ of 53.5 in PEW Science testing.
The subsonic 300 BLK performance of the Liberty Precision Machine Mach-L is detailed in Sound Signature Review 6.164, in which it achieved a composite Suppression Rating of 72.8.
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. 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. Second only to the PTR VENT 1 in gross muzzle signature severity reduction, the Liberty Precision Mach-L achieves its performance through entirely different physical mechanisms. Whereas the Purposely Induced Porosity (PIP) technology in the VENT 1 immediately throttles pressure amplitude and facilitates an expedient blowdown duration, the Mach-L uses the traditional technique of immediate pressure stall with subsequent blowdown delay. Although the net result from both technologies is significant suppression, the methods by which the suppressions are achieved create two distinctly different pressure fields. The comparison of the technologies in the two silencers, and the resulting gross signature suppression performances, highlights the vastness of rifle silencer innovation at the upper echelons of performance.
As the upper echelons of 7.62 NATO suppression performance continue to be stretched, it is 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. Analysis of the test data in PTR, CGS, and CAT test reports, along with the Liberty Precision Machine data herein, strongly supports this conclusion. Silencers like the Nomad-L, Resilient Suppressors Jolene, Diligent Defense Enticer-L, and Otter Creek Labs Hydrogen-L demonstrate high performance, and they also demonstrate technological performance plateaus. The Liberty Precision Machine Mach-L is a more advanced silencer, and its performance demonstrates this fact.
The Mach-L outclasses most silencers in this combustion regime, on this type of weapon system.
The included direct thread mount is easy to install in the Mach-L, and possesses hex-wrench features on the exterior. The mount may be removed and other mounts compatible with the so-called HUB threading system may be installed. This feature allows the Mach-L to be used with a variety of weapon systems.
In this review, the Liberty Precision Machine Mach-L performance metrics depend upon suppressing a supersonic centerfire rifle cartridge; no easy task. PEW Science encourages the reader to remain vigilant with regard to all supersonic centerfire rifle suppression claims. The gas volume and combustion products created by the firing of the supersonic .308WIN cartridge are significant; the measured pressure and impulse magnitudes, and their durations, illustrate this fact.
The hearing damage potential of supersonic centerfire rifle 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.
