SSS.6.123 - PWS BDE 556 and the MK18 5.56x45mm Short Barrel Automatic AR15 Rifle
/Primary Weapons Systems BDE 556 on the MK18 5.56x45mm AR15 with 10.3-in Barrel
The BDE 556 is manufactured by Primary Weapons Systems (PWS). It is a 5.56mm centerfire rifle silencer, intended to suppress the 5.56x45mm cartridge on barrels as short as 10.5 inches in length. The BDE 556 is modular; it may be used in three different length configurations. It has a 1.75-inch diameter and in its longest configuration with no mount, is 6 inches in length. In its shortest configuration, the silencer is 4.9 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 6.5 inches in the longest configuration and 5.4 inches in the shortest configuration. The BDE 556 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 11.6 ounces in the long configuration, 9.6 ounces in the short configuration, and the direct thread mount weighs 1.3 ounces, for total system weights of 12.9 and 10.9 ounces, respectively. The BDE 556 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 for public research 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 white paper was funded in part by PEW Science Project PEW-PWS-033-001-22. Therefore, data pertaining to the BDE 556 in this Sound Signature Review is published with the express written permission of Evolved Gear, LLC (DBA “PWS”).
This Sound Signature Review contains the results from two tests using the BDE 556 with the direct thread mount on the MK18 Automatic AR15 rifle, chambered in 5.56x45mm NATO with a 10.3-inch barrel. Federal XM193 55gr ammunition was used in the tests. The standard PEW Science MK18 test host weapon system is described in Public Research Supplement 6.51.
Section 6.123.1 contains the BDE 556 Long Configuration test results and analysis.
Section 6.123.2 contains the BDE 556 Short Configuration test results and analysis.
Section 6.123.3 contains Suppression Rating comparisons of the BDE 556 in both configurations with dedicated 223 and 30 caliber silencers on the current market, including the CAT ODB, Aero Precision Lahar-30L, Lahar-30, HUXWRX FLOW 762 Ti, Maxim Defense DSX, Thunder Beast Dominus, KAC 5.56 QDC, CGS SCI-SIX, Dead Air Nomad-30, YHM Turbo T2, Dead Air Sandman-S, HUXWRX FLOW 556k, Energetic Armament ARX, KAC QDSS-NT4, Rugged Razor556, Otter Creek Labs Polonium and Polonium-K, Surefire SOCOM556-RC2, HUXWRX HX-QD 556 and HX-QD 556k, Q Trash Panda, CGS Helios QD, SilencerCo Saker 556, Rugged Razor762, and others.
Section 6.123.4 contains an article summary and PEW Science laboratory staff opinions.
Summary: When paired with the 10.3-in barrel MK18 and fired with Federal XM193, the PWS BDE 556 in the long configuration achieved a composite Suppression Rating™ of 36.1 in PEW Science testing. In its short configuration, the BDE 556 achieved a Suppression Rating of 30.8.
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
6.123.1 PWS BDE 556 (Long Configuration) Sound Signature Test Results
A summary of the principal Silencer Sound Standard performance metrics of the BDE 556 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. 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. PWS BDE 556 (Long Configuration) Sound Metric Summary
6.123.1.1 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, the fire control group positioned to single-shot, and the weapon was fired until the magazine was empty and the bolt locked back on 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 public dataset and bolt-closing signatures. 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 6 shots with the PWS BDE 556 in its long 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 6-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 556 (Long Configuration) 5.56x45mm NATO MK18 Automatic Rifle Muzzle Sound Pressure Signature
Fig 1b. PWS BDE 556 (Long Configuration) 5.56x45mm NATO MK18 Automatic Rifle Sound Pressure Signature
Figure 2a. PWS BDE 556 (Long Configuration) 5.56x45mm NATO MK18 Automatic Rifle Muzzle Sound Impulse Signature
Figure 2b. PWS BDE 556 (Long Configuration) 5.56x45mm NATO MK18 Automatic Rifle Muzzle Sound Impulse Signature
The PWS BDE 556, in its long configuration, exhibits high muzzle signature suppression performance and an unusual gas momentum profile (Figure 2) on the 5.56x45mm MK18 weapon system. The behavior is very similar to that exhibited by the somewhat longer PWS BDE 762 on the 7.62x51mm NATO bolt action rifle (6.121.1.1).
The BDE centerfire rifle series, in their long configurations, are characterized by consistent internal combustion and bullet shock events, with a ramped gas jet profile (Fig. 1b). Like the BDE 762, the BDE 556 does exhibit significant first-round-pop (FRP) divergence. However, unlike the BDE 762 on a .308 bolt action rifle, the long configuration of the BDE 556 on the standard MK18 weapon system exhibits an FRP signature that possesses a severity extremely similar to that of subsequent shots.
PEW Science Research Note 1: Although the impulse accumulation in Figure 2 shows significant FRP divergence, its early time jetting is slightly more controlled than in the case of the aforementioned BDE 762 evaluation, and the FRP signature has a somewhat reduced positive phase duration. These factors reduce relative severity of the first shot. It is important to note that this behavior on the MK18 is unique to that of the long configuration of the BDE 556 and using the long configuration of the BDE 762 on the MK18, although it produces a different signature, will not result in the same relative FRP behavior.
PEW Science Research Note 2: Like the long configuration of the BDE 762, the long configuration of the BDE 556 is shown to “throttle” the propagation of gas momentum at low amplitude for an unusually long duration (Fig. 2a). The DMLS silencer core of the BDE 556 possesses a bore dedicated for the 5.56x45mm cartridge, with similar blast baffle porting as the BDE 762. It is important to note that the BDE 556 contains two removable distal baffles in contrast with the BDE 762 which contains four. The bore diameter of the removable baffles in the two silencers is identical.
PEW Science Research Note 3: The long configuration of the BDE 556 exhibits muzzle signature suppression performance that meets or exceeds that of both the Surefire SOCOM556-RC2 (6.52) and the SilencerCo Saker 556 (6.53), which are both also full-size dedicated bore 5.56x45mm silencers. While the BDE 556 does outperform the Saker 556 at the shooter’s ear marginally, it produces a more severe signature at the operator’s head on the untuned MK18 weapon system than does the SOCOM556-RC2. This is a consequence of the silencer’s back pressure. A more in-depth examination of the BDE 556 system back pressure, along with resulting gas dynamics measured at the shooter’s ear, are included in the PEW Science Member version of this review.
The gross signature severity from the long configuration of the BDE 556 on this platform is not unlike that of the Otter Creek Labs Polonium (6.75), but the method by which the two silencers produce that severity is significantly different. And, although the BDE 556 does possess a ported blast baffle array, the gas dynamics are not appreciably less restrictive. Further analysis is given in the Member review.
PEW Science Research Note 4: As in all semiautomatic AR15 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 bolt closing is observed. The pressure signature of Shot 6 does not display this event due to the bolt remaining open after the sixth and final round is fired from the magazine.
PEW Science Research Note 5: The closing time of the MK18 bolt is directly related to the flow restriction of a silencer for a given weapon system. PEW Science has determined bolt closing time variation from the unsuppressed state to be a reliable indicator of silencer back pressure, with strong correlation with the PEW Science Back Pressure Metric, Omega and the alpha parameter. However, PEW Science has also determined that the indicator is unreliable upon upper receiver fouling. Sound signatures are not influenced by this fouling, as these kinematics occur in late time, after gas venting to atmosphere. Momentum transfer, weapon condition (upper receiver fouling), and other factors, can significantly influence bolt closing time. PEW Science urges the reader to exercise extreme caution if using the published bolt closing time to make determinations regarding silencer flow restriction (back pressure) or weapon system kinematics. This type of calculation may provide erroneous results, as the weapon condition at the time of each test is not published data. The time-scale duration showing bolt closing time is only published by PEW Science such that the signature data pedigree may be verified.
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 automatic rifle firearm configuration. It should be noted that there is a pronounced reduction in positive phase impulse, post-peak, during later shots in the string with the BDE 556. The same behavior was noted in the BDE 762 bolt action rifle test. PEW Science postulates this may only normalize after Shot 2 with both silencers due to a distal temperature gradient. More research is needed.
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 Research Note 6: Note that the muzzle Suppression Rating of the long configuration of the BDE 556 is 36.0 and the at-ear Suppression Rating is 18.8; different zones on the Suppression Rating Dose Chart. The lower flow rate (higher back pressure) of the BDE 556 contributes to a more severe ejection port signature, increasing the overall severity of the signature to the shooter on the standard MK18 weapon system. Like all high backpressure systems on untuned host weapons, caution should be exercised by the weapon operator. The signatures measured at the shooter’s ear are presented below.
6.123.1.2 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 are shown in Figure 3. The primary sound signature history is shown in Figure 3a. An annotated timescale is displayed in Figure 3b, for Shots 1, 2, and 4. The real sound impulse (momentum transfer potential) histories at the ear from the same 5-shot test are shown in Figure 4. Again, full and short timescales are shown.
Figure 3a. PWS BDE 556 (Long Configuration) 5.56x45mm NATO MK18 Automatic Rifle Ear Sound Pressure Signature
Figure 3b. PWS BDE 556 (Long Configuration) 5.56x45mm NATO MK18 Automatic Rifle Ear Sound Pressure Signature, Short Time Window
Figure 4a. PWS BDE 556 (Long Configuration) 5.56x45mm NATO MK18 Automatic Rifle Ear Sound Impulse Signature
Figure 4b. PWS BDE 556 (Long Configuration) 5.56x45mm NATO MK18 Automatic Rifle Ear Sound Impulse Signature Peaks
The FRP at the shooter’s ear is somewhat more severe than that to bystanders on this weapon system with the long configuration of the BDE 556. The contribution of ejection port blast is also severe.
PEW Science Research Note 7: Note the erratic positive phase impulse accumulation measured at approximately 34 ms (Fig. 4a). This momentum transfer behavior occurs to due to prolonged positive phase pressure duration at the operator’s head. Typically, with the standard MK18, relatively short duration ejection port blast does not contribute enough positive phase impulse to prolong the overall positive phase accumulation post-muzzle blast. But when backpressure from a silencer system is more severe, and pressure at the ejection port is higher at the time of unlock, wave coalescence from this blast load prevents transition out of the positive phase (Fig. 4b). The consequence of this prolonged blast impulse is a more severe signature for the operator.
Note the late-time rarefaction present in the pressure signature of Shot 4 (Fig. 3b). This behavior follows the long positive phase duration blast pressure during Shot 4, most easily discerned in impulse-space in Figure 4. Rarefaction begins to dominate that signature at approximately 44 ms. These effects are typically not as visible due to ejection port gas momentum dissipating at an earlier time in the signature history, and not contributing to prolonged positive phase accumulation. The BDE 556 exhibits similar behavior, in this way, to other high back pressure silencers like the Otter Creek Labs Polonium (6.75) and SilencerCo Saker 556 (6.53); both of which present extremely similar at-ear signatures.
It is likely that if the standard MK18 weapon system is tuned, the BDE 556 silencer system will achieve higher levels of suppression performance at the shooter’s ear. Weapon tuning is outside the scope of this article. However, the reader is referred to the study of the Maxim Defense DSX SURG System (6.111) for the benefits of such weapon tuning, as applied to the 10.3-in 5.56x45mm automatic rifle. In that test series, effective gas port size as the variable is shown to significantly change signature hazard to the operator.
6.123.2 PWS BDE 556 (Short Configuration) Sound Signature Test Results
A summary of the principal Silencer Sound Standard performance metrics of the BDE 556 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. As stated in Section 6.123.1, 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. PWS BDE 556 (Short Configuration) Sound Metric Summary
6.123.2.1 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 556 (Short Configuration) 5.56x45mm NATO MK18 Automatic Rifle Muzzle Sound Pressure Signature
Fig 5b. PWS BDE 556 (Short Configuration) 5.56x45mm NATO MK18 Automatic Rifle Muzzle Sound Pressure Signature, Short Time Window
Fig 6a. PWS BDE 556 (Short Configuration) 5.56x45mm NATO MK18 Automatic Rifle Muzzle Sound Impulse Signature
Fig 6b. PWS BDE 556 (Short Configuration) 5.56x45mm NATO MK18 Automatic Rifle Muzzle Sound Impulse Signature, Short Time Window
As was the case in the evaluation of the PWS BDE 762 on the 308 bolt action rifle (6.121), the short configuration of the silencer has a significantly different signature than that of the long configuration of the silencer. In its short configuration, the BDE 556 does exhibit similar early time behavior as the longer configuration, with higher amplitude, but the long duration gas momentum throttling does not occur.
PEW Science Research Note 8: Also similarly to the BDE 762, the short configuration of the BDE 556 is susceptible to erratic late-time jetting and this effect becomes more pronounced on the short-barrel MK18. Although the primary DMLS core of the BDE 556 has a dedicated bore for the cartridge, when used on the MK18, the erratic impulse accumulation, post-peak, is somewhat similar to that presented by over-bored 7.62mm silencers on the MK18 weapon system. Public testing of over-bored silencers on the 5.56x45mm MK18 weapon system by PEW Science has demonstrated typical inefficiencies, such as erratic flow rate. Such inefficiency characterized in measured impulse signatures from over-bored silencers may be examined in test reports featuring products such as the Rugged Razor762 (6.58), the Energetic Armament ARX (6.82), the Rugged Razor556 (6.76), the Q Trash Panda (6.61), and the Dead Air Sandman-S (6.92). Despite exhibiting somewhat similar erratic behavior, the short configuration of the BDE 556 still outperforms all of those silencers in gross muzzle suppression on the standard MK18 weapon system.
PEW Science Research Note 9: One of the reasons why the BDE 556 is able to control the secondary combustion from the short barrel MK18 more efficiently than the aforementioned silencers is its dedicated bore. Throughout the shot string, the control is more significant, resulting in smooth decay in Shot 6. However, the signatures do take time to normalize. Gradual decay of the secondary accumulation is noted in Shot 5 in Figure 6b. Shot 3 presents this phenomenon most severely. The blast baffle porting array may contribute to this phenomenon.
The severity of the signature from the BDE 556 does increase with its distal baffles removed. However, its muzzle signature suppression performance still eclipses that of many other silencers tested on the MK18, including the CGS Helios QD (6.66), Q Trash Panda (6.61), KAC QDSS-NT4 (6.78), YHM Turbo T2 (6.98), and the Aero Precision Lahar-30 (6.116). The BDE 556 in this configuration, with its mount, is only 5.4 inches long. That is very similar in size to an Otter Creek Labs Polonium-K (6.95).
The gross flow rate of the BDE 556 also increases when its distal baffle are removed. The below note was given in the BDE 762 bolt action test report:
PEW Science Research Note 10: 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 556 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 PEW Science members, the signatures at the shooter’s ear with the short configuration of the BDE 556 are presented. The lack of a change in alpha, if the parameter is elevated, can significantly degrade a silencer’s backpressure reduction benefits on a semiautomatic rifle. Lowering of distal restriction (dropping Omega), alone, is sometimes not adequate to achieve a desired increase in flow rate.
6.123.2.2 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 BDE 556 in its shortest 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.
Fig 7a. PWS BDE 556 (Short Configuration) 5.56x45mm NATO MK18 Automatic Rifle Ear Sound Pressure Signature
Fig 7b. PWS BDE 556 (Short Configuration) 5.56x45mm NATO MK18 Automatic Rifle Ear Sound Pressure Signature, Short Time Window
Fig 8a. PWS BDE 556 (Short Configuration) 5.56x45mm NATO MK18 Automatic Rifle Ear Sound Impulse Signature
Fig 8b. PWS BDE 556 (Short Configuration) 5.56x45mm NATO MK18 Automatic Rifle Ear Sound Impulse Signature, Short Time Window
The alpha parameter, defined conceptually as the early-time shock and blast reflection and flow rate near the muzzle orifice, controls the ejection port hazard in many silencer systems. As shown in the above figures, the removal of the two distal baffles from the BDE 556 is not enough to significantly reduce the hazard to the weapon operator on this system.
PEW Science Research Note 11: Although the shooter’s ear Suppression Rating does increase marginally, gas momentum transfer remains largely confined to the positive phase during the primary signature. Signifying the more severe muzzle signature, and its contribution to operator hazard, the reader should note the annotation of the Shot 3 impulse in Figure 8b at a time of approximately 32 ms. This muzzle blast contribution to gas momentum accumulation at the operator’s head originates from the same accumulation noted 1.0 m left of the muzzle at approximately 31 ms shown in impulse-space previously in Figure 6. This is an excellent illustration of the duality of hazard origination when using a semiautomatic rifle.
The BDE 556 in the short configuration is slightly less damaging to the shooter’s ear, due to somewhat lower backpressure. However, it is also more severe to bystanders, and thereby also produces a blast load that propagates more severely and impacts the operator. In the case of the BDE 556 - back pressure is controlling shooter inner ear response. Aforementioned weapon tuning may be required for optimal hazard reduction.
6.123.3 Suppression Rating Comparison (5.56x45mm from the MK18)
Figure 9 presents a comparison of the PEW Science Suppression Rating of the two configurations of the BDE 556 to that of other rifle silences on the MK18 automatic AR15 rifle. The standard PEW Science MK18 test host weapon system is described in Public Research Supplement 6.51.
Figure 9. Suppression Rating Comparisons of the PWS BDE 556 and other silencers, Using PEW-SOFT 5.56x45mm Supersonic Test Data and PEW Science Analysis
Figure 9 presents detailed PEW Science Suppression Ratings, computed at the muzzle and ear, for the listed silencers. The Suppression Rating is a holistic parameter that captures human inner ear damage risk potential from a measured impulsive overpressure signature during the entire time regime of weapon operation, including combustion, complete blowdown, and all mechanical operation, including the carrier group returning the battery, in the true free field. The parameter may be used with the dose chart at the beginning of this report.
The long configuration of the BDE 556 exhibits muzzle signature suppression performance that meets or exceeds that of both the Surefire SOCOM556-RC2 (6.52) and the SilencerCo Saker 556 (6.53), which are both also full-size dedicated bore 5.56x45mm silencers. While the BDE 556 does outperform the Saker 556 at the shooter’s ear marginally, it produces a more severe signature at the operator’s head on the untuned MK18 weapon system than does the SOCOM556-RC2. This is a consequence of the silencer’s back pressure. A more in-depth examination of the BDE 556 system back pressure, along with resulting gas dynamics measured at the shooter’s ear, are included in the PEW Science Member version of this review.
The gross signature severity from the long configuration of the BDE 556 on this platform is not unlike that of the Otter Creek Labs Polonium (6.75), but the method by which the two silencers produce that severity is significantly different. And, although the BDE 556 does possess a ported blast baffle array, the gas dynamics are not appreciably less restrictive. Further analysis is given in the Member review.
The severity of the signature from the BDE 556 does increase with its distal baffles removed. However, its muzzle signature suppression performance in its shortest configuration still eclipses that of many other silencers tested on the MK18, including the CGS Helios QD (6.66), Q Trash Panda (6.61), KAC QDSS-NT4 (6.78), YHM Turbo T2 (6.98), and the Aero Precision Lahar-30 (6.116). The BDE 556 in this configuration, with its mount, is only 5.4 inches long. That is very similar in size to an Otter Creek Labs Polonium-K (6.95).
PEW Science Research Note 12: The gross flow rate of the BDE 556 also increases when its distal baffle are removed. However, its proximal geometry does not allow for high early-time flow rate and back pressure influence on weapon function is persistent. Lowering of distal restriction (dropping Omega), alone, is sometimes not adequate to achieve an increase in gross flow rate. This paper serves as a case study illustrating a silencer in which early-time muzzle blast reflection controls system response.
PEW Science Research Note 13: The BDE 556, in both of its configurations, outperforms many silencers tested on the MK18 by PEW Science, to date, in signature hazard reduction to bystanders. Due to the breadth of the Silencer Sound Standard testing and analysis pedigree, the reader is encouraged to examine the spectrum over which suppression performance on the MK18 has been demonstrated. There exist silencers evaluated on the 5.56x45mm short barrel rifle platform that have significantly lower performance. 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 - it is not a subjective quantity; it is an objective quantification of hearing damage risk potential.
As shown in Figure 9, the Suppression Rating at the shooter’s ear may be significantly influenced by the ejection port signature from the MK18; all other things equal. For details on performance increases that are possible when “tuning” an AR-15 weapon system for a silencer, please see Review 6.111. It is important to note that not all silencers will possess a significant increase in shooter’s ear Suppression Rating from weapon tuning. Signature at the operator’s head is a function of both muzzle and ejection port signatures from the AR-15 weapon system. Specific weapon system parameters will dictate modification efficacy.
6.123.4 Review Summary: PWS BDE 556 on the MK18 5.56x45mm AR15 with 10.3-in Barrel
When paired with the 10.3-in barrel MK18 and fired with Federal XM193, the PWS BDE 556 in the long configuration achieved a composite Suppression Rating™ of 36.1 in PEW Science testing. In its short configuration, the BDE 556 achieved a Suppression Rating of 30.8. 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 556 is a modular 5.56mm centerfire rifle silencer that may be configured as full-size or compact. The silencer possesses relatively high gross suppression performance in both its longest and shortest configurations, on the standard MK18 weapon system, while possessing higher back pressure compared to some designs. It is a titanium silencer of hybrid design, constructed with both DMLS and traditional subtractive manufacturing. With three different configurations, the BDE 556 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.
Like the BDE 762 from Primary Weapons Systems, the hybrid design of the BDE 556 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 556 has varied performance, depending on the configuration selected by the user. It possesses two 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 long configuration of the BDE 556 exhibits muzzle signature suppression performance that meets or exceeds that of both the Surefire SOCOM556-RC2 and the SilencerCo Saker 556, which are both also full-size dedicated bore 5.56x45mm silencers. While the BDE 556 does outperform the Saker 556 at the shooter’s ear marginally, it produces a more severe signature at the operator’s head on the untuned MK18 weapon system than does the SOCOM556-RC2. This is a consequence of the silencer’s back pressure.
The severity of the signature from the BDE 556 does increase with its distal baffles removed. However, its muzzle signature suppression performance in its shortest configuration still eclipses that of many other silencers tested on the MK18, including the CGS Helios QD, Q Trash Panda, KAC QDSS-NT4, YHM Turbo T2, and the Aero Precision Lahar-30. The BDE 556 in this configuration, with its mount, is only 5.4 inches long. That is very similar in size to an Otter Creek Labs Polonium-K.
The gross flow rate of the BDE 556 also increases when its distal baffle are removed. However, its proximal geometry does not allow for high early time flow rate and back pressure influence weapon function is persistent. Lowering of distal restriction (dropping Omega), alone, is sometimes not adequate to achieve a desired increase in flow rate.
The rear mount threading of the PWS BDE 556 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 556 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 PWS BDE 556 performance metrics depend upon suppressing a supersonic centerfire rifle cartridge on a short barrel gas-operated rifle, which is an incredibly difficult 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 5.56x45mm cartridge are significant; the measured pressure and impulse magnitudes, and their durations, illustrate this fact. Silencer performance on automatic (reciprocating) rifles depends on many factors. Weapon configuration may significantly influence total suppressed small arm system performance.
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.
