SSS.6.121 - PWS BDE 762 and the Savage Model 10 PC .308 (Free Version)
/Primary Weapons Systems BDE 762 on a Savage Model 10 .308 with 20-in Barrel
The BDE 762 is manufactured by Primary Weapons Systems (PWS). It is a 30 caliber centerfire rifle silencer, intended to suppress many cartridges with projectiles appropriately sized to travel through the bore, up to and including 300 Winchester Magnum. The BDE 762 is modular; it may be used in five different length configurations. It has a 1.75-inch diameter and in its longest configuration with no mount, is 8.3 inches in length. In its shortest configuration, the silencer is 6.1 inches in length. The rear of the silencer is threaded with the so-called HUB universal diameter and pitch, allowing the use of a variety of mounting solutions. With the included direct thread mount, the silencer’s length increases to 8.8 inches in the longest configuration and 6.6 inches in the shortest configuration. The BDE 762 is of hybrid construction; the primary expansion (blast) chamber and primary baffle section are DMLS Titanium. The distal modular baffles and end cap assembly are traditionally machined Titanium. As tested, the silencer weighs 15.6 ounces in the long configuration, 11.5 ounces in the short configuration, and the direct thread mount weighs 1.2 ounces, for total system weights of 16.8 and 12.7 ounces, respectively. The BDE 762 can be obtained from Silencer Shop.
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 data production for this Sound Signature Review was funded in part by PEW Science Project PEW-PWS-033-001-22. Therefore, data pertaining to the BDE 762 in this Sound Signature Review is published with the express written permission of Evolved Gear, LLC (DBA “PWS”).
This review contains the results from two tests using the BDE 762 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 6.121.1 contains the BDE 762 Long Configuration test results and analysis.
- Section 6.121.2 contains the BDE 762 Short Configuration test results and analysis.
- Section 6.121.3 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 4 through 6. 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 6.121.4 contains the review summary and PEW Science opinions.
Summary: When paired with the Savage M10 20” .308 and fired with Federal XM80, the PWS BDE 762 in the long configuration, mounted with the direct thread mount, achieved a Suppression Rating™ of 48.7 in PEW Science testing. In its short configuration, the BDE 762 achieved a Suppression Rating of 40.4. 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
6.121.1 PWS BDE 762 (Long Configuration) Sound Signature Test Results
A summary of the principal Silencer Sound Standard performance metrics of the BDE 762 in its longest 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. 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. PWS BDE 762 (Long Configuration) Sound Metric Summary
6.121.1.1 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 BDE 762 in its longest configuration are shown in Figure 1a. The sound signatures of Shot 1 and Shot 2 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 2 and Shot 3.
Fig 1a. PWS BDE 762 (Long Configuration) Bolt Action Rifle Muzzle Sound Pressure Signature
Fig 1b. PWS BDE 762 (Long Configuration) Bolt Action Rifle Muzzle Sound Pressure Signature, Short Time Window
Figure 2a. PWS BDE 762 (Long Configuration) Bolt Action Rifle Muzzle Sound Impulse Signature
Figure 2b. PWS BDE 762 (Long Configuration) Bolt Action Rifle Muzzle Sound Impulse Signature, Short Time Window
Figure 1b shows a 2.4 millisecond long portion of the first round sound pressure signature of the BDE 762 in its longest configuration, as measured 1.0 m left of the muzzle. There are several significant waveform features labeled:
Internal combustion within the silencer reaches a peak of 125.1 dB.
The end cap exit event, consisting of bullet shock and the initial jet, results in a peak overpressure magnitude of 141.1 dB.
There is relatively early FRP divergence; primary first-round-pop (FRP) jetting reaches an early peak magnitude of 148.7 dB.
Note the low amplitude long duration decay of all shot histories after the primary jet events (ref. Fig. 2).
This is a somewhat unusual sequence observed when firing supersonic .308WIN ammunition from a bolt-action rifle with an attached silencer that exhibits relatively moderate flow restriction (back pressure). Internal silencer design can significantly influence the measured timing and pressure amplitudes. Preliminary back pressure comparisons are shown in Section 6.121.3 of this review, with the PEW Science Back Pressure Metric, Ω [Pa-1]. Note that 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 future research. For example, the BDE 762 possesses a ported blast baffle configuration in the DMLS section, and when used with the included direct-thread mount, early time gas dynamics and their influence on weapon function may differ from some silencers present in the same Omega Zone.
The PWS BDE 762, in this combustion regime, demonstrates high performance sound suppression characteristics. An unusual aspect of its performance is its external gas momentum accumulation profile (impulse, Figure 2). The BDE 762 does build external gas momentum expediently, but is shown to “throttle” the propagation at low amplitude for an unusually long time duration. It does this after a relatively significant FRP impulse accumulation (ref. Fig. 2a). The BDE 762 may exhibit FRP that is up to approximately 40% more severe than subsequent shots to bystanders, on this platform, than subsequent shots.
The flow rate of the BDE 762 is higher than typical for its overall suppression performance. In its longest configuration, the BDE 762 produces a signature severity on this platform that is similar to that of the Otter Creek Labs Hydrogen L (6.81) and the Abel Company Theorem-L (6.117). This is unusual, given its Omega Metric.
PEW Science Research Note 1: The porting array in the first DMLS proximal baffle section of the BDE 762 produces gas dynamics that are postulated to result in some of the initial jetting behavior noted above. Post-FRP behavior in early time (ref. Fig. 2b) is relatively consistent with latent accumulation also relatively consistent as the shot string continues. Although erratic jetting does present in early time, flow presents as normalized, post peak.
PEW Science Research Note 2: Like the Abel Company Theorem-L, the PWS BDE 762 possesses certain features to assist with achieving consistent gas dynamics, including a symmetrical blast baffle. The distal baffles of the BDE 762 possess symmetrically staggered notches. The combination of these features may result in requisite precision improvements; however, PEW Science has not evaluated the influence of this silencer on weapon precision.
Consistent with these measured pressure and impulse waveform features, the computed PEW Science Omega Metric is relatively moderate, placing the long configuration of the silencer in Omega Zone 6. Relative Suppression Rating and flow restriction (back pressure) data is presented in Section 6.121.2 of this review, for both the long and short configurations of the BDE 762.
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.
6.121.2 PWS BDE 762 (Short Configuration) Sound Signature Test Results
A summary of the principal Silencer Sound Standard performance metrics of the BDE 762 in its shortest 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. 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 2. PWS BDE 762 (Short Configuration) Sound Metric Summary
6.121.2.1 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 BDE 762 in its shortest configuration are shown in Figure 5a. The sound signatures of Shot 1 and Shot 2 are shown in a smaller 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, Shot 3, and Shot 4.
Fig 5a. PWS BDE 762 (Short Configuration) Bolt Action Rifle Muzzle Sound Pressure Signature
Fig 5b. PWS BDE 762 (Short Configuration) Bolt Action Rifle Muzzle Sound Pressure Signature, Short Time Window
Fig 6a. PWS BDE 762 (Short Configuration) Bolt Action Rifle Muzzle Sound Impulse Signature
Fig 6b. PWS BDE 762 (Short Configuration) Bolt Action Rifle Muzzle Sound Impulse Signature, Short Time Window
In its shortest configuration, the signature from the PWS BDE 762 is significantly different than from its longest configuration. While much of the phenomenology of its combustion propagation changes, the signatures do possess some features that remain constant. For example:
The early time wave shape is somewhat similar.
Immediate jetting occurs, without delay, at a similar rate.
In contrast to the long configuration, the short configuration then:
Continues to build a higher amplitude jet.
Produces blowdown at a higher rate.
Has less severe FRP at the muzzle.
Has potential for somewhat erratic late-time jetting.
PEW Science Research Note 6: The above performance factors are not unexpected for a silencer with a distal baffle section removed. The early-time gas propagation through the silencer remains unchanged, and to a weapon system, its so-called alpha parameter remains constant. However, the later time gas propagation loses a significant duration component. This is a visual illustration of a drop in the Omega Metric in two silencer configurations. And, because the proximal end of the BDE 762 in the longest and shortest configurations is the same (alpha is constant), a drop in Omega directly correlates with a drop in back pressure. Case studies such as this are somewhat uncommon, but available in the Silencer Sound Standard public research pedigree. The reader may refer to technical reports illustrating the performance of the following silencers for a demonstration of constant alpha with direct Omega backpressure scaling:
For 7.62x51mm cases 1 through 4, the Omega variation is presented in Figure 10 of this report. Note that case 5 is a 5.56x45mm case study.
6.121.3 Relative Suppression Rating and Back Pressure Comparisons (.30 Rifle Silencers)
The PWS BDE 762 suppressor is intended to offer significant sound signature suppression in multiple configurations, while offering somewhat lower back pressure than similarly sized designs. 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 3, 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 future research.
- The Back Pressure Metric relations are most easily viewed on a logarithmic scale (See Figure 6).
Figure 9. 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 10. 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 3. 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 future research. For example, the PWS BDE 762 possesses a ported blast baffle array, and when used with the included direct-thread mount, early time gas dynamics and their influence on weapon function may differ from some silencers present in Omega Zones 4 and 6.
Long Configuration Comparisons: The suppression performance of the BDE 762 in its longest configuration on this platform, holistically, is best compared with the Abel Company Theorem-L (6.117) and the Otter Creek Labs Hydrogen L (6.81). The BDE 762 eclipses the performance of the Aero Precision Lahar-30L (6.112), Thunder Beast ULTRA 9 (6.24) and the Otter Creek Labs PR30L (6.48), on this platform. It is important to note that in its longest configuration, with the included direct thread mount, the PWS BDE 762 is 8.8 inches long.
Short Configuration Comparisons: In its shortest configuration, the performance of the BDE 762 drops to levels of the Richmond Tactical RT30Ti (6.34), the Dead Air Sandman-Ti (6.19), the Q Thunder Chicken (6.20), the Dead Air Nomad-Ti (6.44), and the HUXWRX FLOW 762 Ti (6.113). The length of the BDE 762 in this configuration, with the included direct thread mount, is 6.6 inches.
PEW Science Research Note 8: The PWS BDE 762 possesses four distal baffles that are removable. As the amount of baffles are reduced, the Suppression Rating at the muzzle and shooter’s ear will drop. In the interest of practicality and to bound this performance envelope, the silencer was only tested in the longest and shortest configurations. Interpolation of performance parameters between these two extremes may be performed. However, the user is cautioned that the performance scaling is most likely nonlinear.
PEW Science Research Note 9: The BDE 762 is in Omega Zone 6 in its longest configuration and Zone 4 in its shortest configuration, which indicates that it exhibits a variable and relatively moderate flow restriction. Interior expansion volume, coupled with the quantity and number of baffles, contribute to this lower flow rate.
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.
It is extremely important to note that peak sound pressure [dB], peak sound impulse [dB-ms], and Omega (Ω) [Pa-1], alone, do not determine the sound supression performance of a silencer. It is the combination of these and other waveform parameters that form the total sound signature and the influence on human inner ear response. The PEW Science Suppression Rating computation considers all of these factors.
6.121.4 Review Summary: PWS BDE 762 on a Savage Model 10 .308 with 20-in Barrel
When paired with the Savage M10 20” .308 and fired with Federal XM80, the PWS BDE 762 in the long configuration, mounted with the direct thread mount, achieved a Suppression Rating™ of 48.7 in PEW Science testing. In its short configuration, the BDE 762 achieved a Suppression Rating of 40.4. As with all weapon systems, the user is encouraged to examine both muzzle and ear Suppression Ratings.
PEW Science Laboratory Staff Opinion:
The PWS BDE 762 is a modular 30 caliber rifle silencer that may be configured as full-size or compact. The silencer possesses relatively high suppression performance in both its longest and shortest configurations, on a centerfire rifle. It is a titanium silencer of hybrid design, constructed with both DMLS and traditional subtractive manufacturing. With five different configurations, the BDE 762 is relatively unique as a modular rifle silencer and also possesses a modular rear mounting interface that may be used with a variety of mounting solutions and muzzle devices.
The PWS BDE 762 possesses certain features to assist with achieving consistent gas dynamics, including a symmetrical blast baffle. The distal baffles of the BDE 762 possess symmetrically staggered notches. The combination of these features may result in requisite precision improvements; however, PEW Science has not evaluated the influence of this silencer on weapon precision.
The hybrid design of the BDE 762 is indicative of an evolving silencer market. Geometry in the DMLS (3D-printed) proximal section of the silencer, particularly its porting array, is somewhat more complex than typically fielded with subtractive manufacturing. Where traditional manufacturing is practical, the rest of the silencer’s design takes advantage. A modular silencer, the BDE 762 has varied performance, depending on the configuration selected by the user. It possesses four distal baffles that are removable. As the amount of baffles are reduced, the Suppression Rating at the muzzle and shooter’s ear will drop. Interpolation of performance parameters between the two tested extremes may be performed. However, the user is cautioned that the performance scaling is most likely nonlinear.
The suppression performance of the BDE 762 in its longest configuration on this platform, holistically, is best compared with the Abel Company Theorem-L and the Otter Creek Labs Hydrogen L. The BDE 762 eclipses the performance of the Aero Precision Lahar-30L, Thunder Beast ULTRA 9, and the Otter Creek Labs PR30L, on this platform. It is important to note that in its longest configuration, with the included direct thread mount, the PWS BDE 762 is 8.8 inches long.
In its shortest configuration, the performance of the BDE 762 drops to levels of the Richmond Tactical RT30Ti, the Dead Air Sandman-Ti, the Q Thunder Chicken, the Dead Air Nomad-Ti, and the HUXWRX FLOW 762 Ti, on this weapon system. The length of the BDE 762 in this configuration, with the included direct thread mount, is 6.6 inches.
The rear mount threading of the PWS BDE 762 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 BDE 762 may be influenced by mounting system choice. The user’s choice of mount may balance system weight, length, durability, utility, and even back pressure of the silencer. The data presented by PEW Science in this Sound Signature Review was measured with the direct thread mount with both tested configurations of the silencer.
In this review, the BDE 762 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.
