SSS.6.3 - EA Vox S and the Savage M10 PC .308
/Energetic Armament Vox S on a Savage Model 10 .308 with 20-in Barrel
The Vox S is manufactured by Energetic Armament. It is a 30 caliber centerfire rifle silencer, intended to suppress most cartridges with projectiles appropriately sized to travel through the bore, including 300 RUM. It has a 1.55-inch diameter and is 5.9 inches in length when using the direct-thread adapter. The user may choose to use other third-party adapters compatible with the 1.375”-24tpi system. The silencer is tubeless and constructed of heat treated C300 nickel-cobalt maraging alloy, with the end cap and direct thread adapter being constructed of 17-4 PH stainless steel and Grade 5 titanium, respectively. The silencer weighs 12.5 ounces with the direct thread adapter. An optional wipe and wipe-retainer may be used which increase the weight by 0.4 ounces. The Vox S can be obtained by your local dealer from the distributor Allen Arms Tactical.
This review contains single-test results using the Vox S on the Savage Model 10 Precision Carbine rifle, chambered in .308WIN with an 20-inch barrel. Federal XM80C 149gr ammunition was used in the test.
Summary: When paired with the Savage M10 20” .308 and fired with Federal XM80C, the EA Vox S in the direct-thread configuration achieved a Suppression Rating™ of 29.5 in PEW Science testing.
6.3.1 Vox S Sound Signature Test Results (Direct Thread)
A summary of the principal Silencer Sound Standard performance metrics of the Vox S in its direct thread configuration 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. EA Vox S (Direct Thread Configuration) Sound Metric Summary
6.3.1.1 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 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, here.
Figure 1 shows an approximately 1-millisecond long sequence of events during the first test shot of the Vox S, as measured 1.0 m left of the muzzle. There are four significant events shown:
The firing pin drops to hit the primer, causing a 116.1 dB peak.
The next peak of 139.8 dB occurs as bullet exits the end-cap and the combustion products start to exit the silencer.
The muzzle blast jetting continues to propagate through the silencer.
Jetting increases out of the silencer end-cap, and a 150.0 dB peak occurs. The complete volume of combustion gasses has not yet exited the silencer; the highest peak from that event occurs later, at 31 milliseconds, with an amplitude of 150.8 dB.
This is the typical sequence observed when firing supersonic .308WIN ammunition from a bolt-action rifle with an attached silencer; however, internal silencer design can significantly influence the measured timing and pressure amplitudes.
Fig. 1 Early-Time Shot History, EA Vox S Direct Thread Configuration Bolt Action Rifle Muzzle Sound Pressure Signature, 16-APR-2020
The primary sound signature pressure histories for all 5 shots are shown in Figure 2a. A zoomed-in timescale displays the region of peak sound pressure in Figure 2b. The real sound impulse (momentum transfer potential) histories from the same 5-shot test are shown in Figure 3. Again, full and short timescales are shown.
Fig 2a. EA Vox S Direct Thread Configuration Bolt Action Rifle Muzzle Sound Pressure Signature, 16-APR-2020
Fig 2b. EA Vox S Direct Thread Configuration Bolt Action Rifle Muzzle Sound Pressure Signature, Short Time Window, 16-APR-2020
Figure 3a. EA Vox S Direct Thread Configuration Bolt Action Rifle Muzzle Sound Impulse Signature, 16-APR-2020
Figure 3b. EA Vox S Direct Thread Configuration Bolt Action Rifle Muzzle Sound Impulse Signature, 16-APR-2020
Figure 2 shows a significant pressure regime first-round-pop (FRP). Note, however, the similarity in pressure magnitude of the combustion event early in time between Shot 1 and Shot 2. Another way to view this constant phenomenon is to examine the early-time momentum transfer potential (impulse) in Figure 3. The small blip and plateau occurring at approximately 30 milliseconds is very similar in each shot when viewed in the impulse regime. The overall sound signature, however, differs after the first shot in both pressure and impulse space, solidifying the FRP conclusion, and should clearly illustrate what can change with silencer performance with a particular design and what can’t, from shot to shot.
Although it may be possible to reduce FRP, the events prior to the entrance of gasses into the silencer are dependent upon the host weapon, and the behavior of the gasses within the silencer are dependent upon the internal silencer design. The FRP phenomenon in the pressure regime (Figure 2b) is clearly illustrated between 30.0 and 30.2 milliseconds, after the combustion from the barrel has already entered the silencer, but before the full gas volume has completely exited the silencer. This is a true visual representation of sound pressure difference due to internal silencer gas environment.
PEW Science note: First-round sound signatures always differ from subsequent shots, as the atmosphere within the silencer changes. The FRP phenomenon cannot always be shown by viewing only the peak sound pressure. This is one of the reasons why The Silencer Sound Standard requires examining multiple sound signature metrics. The earlier impulse peak arrival time in Figure 3b further illustrates the potential difference of a first shot in a string of shots. Furthermore, it is again important to note that there is a baseline-level of sound signature suppression possible with certain silencer designs at various times during the shot sequence; the constant impulse plateaus at approximately 30 ms illustrate this. Further suppression of this part of the sound signature is not possible without changing ammunition or modifying the silencer design.
6.3.1.2 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 4. 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 5. Again, full and short timescales are shown.
Figure 4a. EA Vox S Direct Thread Configuration Bolt Action Rifle Ear Sound Pressure Signature, 16-APR-2020
Figure 4b. EA Vox S Direct Thread Configuration Bolt Action Rifle Ear Sound Pressure Signature, Short Time Window, 16-APR-2020
Figure 5a. EA Vox S Direct Thread Configuration Bolt Action Rifle Ear Sound Impulse Signature, 16-APR-2020
Figure 5b. EA Vox S Direct Thread Configuration Bolt Action Rifle Ear Sound Impulse Signature, 16-APR-2020
Similar to the measurements at the muzzle, there is FRP evident when examining the waveforms measured at the shooter’s ear, particularly the impulse (Figure 5b). Note that, again, the fast rise-time to peak impulse after silencer gas exit is evident in Shot 1. Also note the very similar pressure and impulse magnitudes during Shot 1 and Shot 2 prior to the gas completely exiting the silencer. The supersonic .308WIN platform creates significant sound signature even before the gas completely exits the silencer.
The overall sound signature measured at the shooter’s ear possesses significantly less amplitude in both the pressure and impulse regimes than the signature measured at the muzzle (refer to Table 1). Furthermore, the application of both pressure and impulse at the shooter’s ear is delayed when compared to the pressure and impulse at the weapon muzzle. The combination of varying amplitude and rise time to peak amplitude influences the response of the human ear.
6.3.2 Review Summary: Energetic Armament Vox S on a Savage Model 10 .308 with 20-in Barrel
When paired with the Savage M10 20” .308 and fired with Federal XM80C, the EA Vox S in the direct-thread configuration achieved a Suppression Rating™ of 29.5 in PEW Science testing.
PEW Science Subjective Opinion:
The EA Vox S is a machine gun rated silencer with a diameter and weight conducive to dual-use on semiautomatic or bolt-gun hosts. The ability to configure the silencer mounting scheme differently based upon mount type preferences may be attractive to some users. The silencer is not the quietest on the market, but is advertised as being extremely durable. C300 material properties after continued temperature cycles within the temperature regimes of supersonic centerfire rifle semi- and fully-automatic firing schedules have not been evaluated by PEW Science and are a subject of continued research interest. The durability of the various third-party mounts that interface with the Vox S are also a subject of research interest, as silencer durability is a function of the entire suppressed weapon system.
The wiped end-cap is an interesting addition to this silencer and has not yet been evaluated by PEW Science. The capability to use a wipe may be attractive to some users. PEW Science postulates the the greatest sound signature reduction potential with wipe use will be realized when using subsonic cartridges such as subsonic 300BLK.
In this review, the EA Vox 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.
