SSS.6.202 - Zastava ZVUK and the 7.62x39mm Automatic Serbian AK-Pattern Rifle (Free Version)

/

Zastava ZVUK on the Zastava ZPAPM70 AK-Pattern Rifle with 16.3-in Barrel

The ZVUK is a 30 caliber centerfire rifle silencer manufactured by Zastava Arms USA.  The ZVUK is intended to suppress weapons originating in the former Soviet Union, including AK-pattern reciprocating rifles, with both semiautomatic and automatic fire; it is a 3D-printed tribute to the Soviet Pribor Besshumnoy Stryelbiy (PBS) silencer system. It has a 1.59-inch forward diameter and is 7.63 inches long with no mount.  The silencer is "HUB” compatible and the included direct-thread mount increases the silencer’s total length to 7.94 inches. The entirety of the ZVUK structure is monolithic and constructed from 3D Printed titanium alloy. The silencer weighs 11.4 ounces and the included direct thread mount weighs 1.9 ounces, for a total system weight of 13.3 ounces, as tested. The ZVUK 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 analysis production for this Sound Signature Review was funded in part by PEW Science Project PEW-Zastava-118-001-25. Therefore, data pertaining to the ZVUK in this Sound Signature Review is published with the express written permission of Zastava Arms USA.

The testing and analysis presented in this Sound Signature Review are of the ZVUK on the Zastava ZPAPM70 16.3-in barrel stamped bulged trunnion receiver Serbian (Yugoslavian-pattern) import, chambered in 7.62x39mm with a 16.3-inch barrel. Hornady American Gunner 123gr ammunition was used in the test. The three standard AK-pattern host weapon systems are described in Public Research Supplement 6.200.

Report Table of Contents:

  • Section 6.202.1 contains an abbreviated overall summary of Zastava ZVUK suppression performance on the AK-pattern rifle system and comparisons with the Dead Air Wolverine.

  • Section 6.202.2 contains ZVUK 16.3-in barrel Yugoslavian-pattern AK test results and analysis.

  • Section 6.202.3 provides overall Suppression Rating comparisons.

  • Section 6.202.4 contains a report summary and PEW Science laboratory staff opinions.

Summary: When paired with the Zastava ZPAPM70 and fired with Hornady American Gunner 123gr 7.62x39mm ammunition, the Zastava ZVUK achieved a Suppression Rating™ of 33.7 in PEW Science testing.

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.

6.202.1 Zastava ZVUK 7.62x39mm AK-Pattern Rifle Performance Summary

With this report, the PEW Science Silencer Sound Standard continues 7.62x39mm AK-pattern rifle silencer performance evaluation.  The test data and analysis herein covers the Zastava ZVUK on a Yugoslavian full-size AK-pattern rifle; the same Yugoslavian pattern rifle on which the Dead Air Wolverine (6.201) was previously evaluated.  In addition to comparing the ZVUK and Wolverine suppression performance, the Suppression Ratings can be compared with those of other platforms, as the Ratings are universal risk metrics. Comprehensive performance Rankings are tabulated in Section 7 of the Standard.

As typical, the risk metrics expressed by Suppression Rating for the unsuppressed cases and the suppressed cases are shown below in Figure 1.

Figure 1. Suppression Rating Comparisons of the Zastava ZVUK and Dead Air Wolverine Using PEW-SOFT 7.62×39mm Supersonic AK Test Data and PEW Science Analysis

From the above 7.62x39mm AK-pattern rifle performance metrics, it can be concluded that these systems can be significantly hazardous to both the operator and bystanders, even when suppressed.  Note the performance metrics presented are of only two silencers.  Further AK-pattern rifle testing and analysis with other silencer models is forthcoming.

Several key observations can be made from the above:

  1. Both the ZVUK and Wolverine are tributes to the legacy Soviet PBS system, in gross exterior design envelope. They are also both more advanced than the legacy system. However, the level of advancement between the two modern designs differs. The Dead Air Wolverine uses curved and stepped cone baffles with significant over-bore with no ancillary vent structures, whereas the Zastava ZUK uses a monolithic printed design possessing stepped baffles combined with Purposely Induced Porosity (PIP), along with early blast chamber venting and secondary flow paths.  These design differences result in significantly higher pure suppression performance from the ZVUK, with a higher gross flow rate.

  2. The higher flow rate of the ZVUK pays personnel hazard reduction dividends on the full size AK-pattern rifle. As the rifle system has significant dwell time, reduction in early time blast load impulse accumulation in close proximity to the barrel muzzle orifice inside the silencer reduces the effective blast impulse transfer to the piston assembly through the barrel gas port. With less piston impulse in early time, the system reciprocation is somewhat delayed, reducing (but not eliminating) the propensity for adverse blast overpressure to impact the operator from the weapon breech.

  3. Both systems produce operator risk metrics that are lower than typically desirable on a standard reciprocating suppressed centerfire rifle system. As more silencer models are evaluated on the AK-platform, the gross and localized suppression performance potentials of the platform will be explored.

The detailed 7.62x39mm AK-pattern rifle evaluation of the Zastava Arms USA ZVUK silencer follows.

6.202.2 Zastava ZVUK 16.3-in Barrel Serbian (Yugoslavian) AK-Pattern Rifle Sound Signature Test Results

A summary of the principal Silencer Sound Standard performance metrics of the Zastava ZVUK on the 16.3-in Barrel Zastava ZPAPM70 Serbian (Yugoslavian) AK-pattern rifle 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. Zastava ZVUK 16.3-in Yugoslavian AK Sound Metric Summary

 

6.202.2.1 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. 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 Zastava ZVUK are shown in Figure 2a. 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 3a. In Figure 3b, a shorter timescale is shown comparing the impulse of Shot 1 to that of Shots 2 and 3.

Fig 2a. Zastava ZVUK 7.62×39mm 16.3-in barrel Yugoslavian AK Muzzle Sound Pressure Signature

Fig 2b. Zastava ZVUK 7.62×39mm 16.3-in barrel Yugoslavian AK Sound Pressure Signature

Figure 3a. Zastava ZVUK 7.62×39mm 16.3-in barrel Yugoslavian AK Muzzle Sound Impulse Signature

Figure 3b. Zastava ZVUK 7.62×39mm 16.3-in barrel Yugoslavian AK Muzzle Sound Impulse Signature

Like the previously evaluated Dead Air Wolverine (6.201), the Zastava ZVUK is a modern tribute to the Soviet Pribor Besshumnoy Stryelbiy (PBS) silencer system [English: “Device for Noiseless Shooting"].  Unlike the original PBS silencer design(s), both the Wolverine and the ZVUK use modern baffle technology, materials, and construction.  The ZVUK is more advanced than the Wolverine, in that it uses a monolithic printed design possessing stepped baffles combined with Purposely Induced Porosity (PIP) under license, along with early blast chamber venting and secondary flow paths.  These design differences result in significantly higher pure suppression performance from the ZVUK, with a higher gross flow rate.  The ZVUK is quieter than the Wolverine, with lower back pressure.

The free field blast pressure and impulse signatures presented above display the following attributes:

  1. Free field blast overpressure blowdown duration is relatively short, bolt carrier group (BCG) impact at the end of its first path of travel is somewhat delayed, and BCG return occurs somewhat later time (Fig. 2a).

  2. Defined first precursor and coupled jet formation is present in all shots, with more significant precursor amplitude than previously noted (Fig. 2b).

  3. First-round-pop (FRP) combustion diverges early, with rapid momentum accumulation, and the difference from subsequent shots in the string is significant.  Divergence continues after maximum positive phase accumulation.  Post-FRP consistency is high (Fig. 3b).

PEW Science Research Note 1: The performance differential between the Zastava ZVUK and the Dead Air Wolverine is somewhat expected and largely unremarkable when considering the technology generations present in both the silencers. Performance factors of note that bear highlighting are the slower weapon kinematics from the reduced back pressure, the lower personnel risk from more advanced signature suppression of the blast overpressure events, the reduced ejection port blast, and the post-FRP consistency. The Zastava ZVUK is a hybrid design utilizing PIP.  The reader is encouraged to review the technical performance factors associated with PIP technology in past research.

PEW Science Research Note 2: It is also important to note that the FRP produced by the ZVUK is noticeable and persistent. This phenomenon can subject bystanders adjacent to the weapon system to risk that is approximately 40 percent more severe during the first shot compared to subsequent shots, with this silencer on this weapon system.  The Dead Air Wolverine has less severe relative FRP, but every shot from the Wolverine is more severe than even the ZVUK’s FRP.  Further details and performance comparisons of these metrics will be presented in a PEW Science Member Research Supplement for AK-pattern rifles.

PEW Science Research Note 3: The reader should note that hybrid technology silencer design is not simply limited to certain technology implementations.  For example, the utilization of PIP in a silencer does not necessarily result in an extremely elevated flow rate that reduces system back pressure such that adverse ejection port blast loads are immediately nullified. On the contrary, holistic system performance depends on how certain technologies are implemented in a silencer, and how they behave alongside other design factors. In the Zastava ZVUK, there are design factors that prevent the system from exhibiting an extremely elevated flow rate, but there is a given performance balance exhibited by the design that may be appropriate for many users. The balance of overall performance, early-time flow rate, distal flow rate, and back pressure reduction, varies between each silencer technology. This was demonstrated relatively recently when comparing the PTR VENT Spiritus 556i (6.176) and the Dillon DRC556 (6.194) on the 14.5-in 5.56x45mm NATO M4 mid-length gas AR-15.  Both those silencer possess similar technologies and designs.  However, the implementation of certain features in each of the two silencer designs results in the DRC556 possessing higher early time flow restriction than the Spiritus.  With proper weapon tuning, the DRC may be capable of meeting or exceeding the performance of the Spiritus; the performance differentials are a function of the holistic suppressed small arm weapon system.

PEW Science Research Note 4:  Relative cross-platform comparisons of bystander and shooter risk are possible with the PEW Science Suppression Rating.  The following systems exhibit similar risk to bystanders to the ZVUK on the Zastava ZPAPM70 7.62x39mm AK-pattern rifle, 1.0 meter left of the silencers’ end caps, in the true free field:

PEW Science Research Note 5:  It is extremely important for the reader to understand the Suppression Ratings are computed with free field test data, and are therefore universal when translating the weapon and operator to different environments without reflections.  However, when the environment becomes complex with many reflecting surfaces, performance translation of different systems is not yet possible; sound field shapes and particle velocities result in varied blast wave time-of-arrivals, as well as changes of blast load angles of incidence; these variations change amplitude and phase waveform components.  As a result of these inevitable environmental complexities, user impressions will vary, as both the shooter and bystander.  Nonetheless, hazard reduction efficacy in the free field, as characterized by the Suppression Rating, holds.  The Suppression Rating comparisons are the current state-of-the-art, and the most “apples to apples” sound suppression performance comparisons that currently exist.  Further research is ongoing.

PEW Science Research Note 6: As in all semiautomatic 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 112 ms in Figure 1a) the mechanical noise of the bolt closing is observed. The pressure signature of Shot 6 also displays this event because this AK platform does not posses a “bolt hold open” feature after the sixth and final round is fired from the magazine.

PEW Science Research Note 7: The closing time of reciprocating systems is often 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.

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 8: Note that the muzzle Suppression Rating of the Zastava ZVUK on this 16.3-in AK-pattern rifle is 33.5 and the at-ear Suppression Rating is 16.5; the same zone on the Suppression Rating Dose Chart.  The muzzle blast suppression of the ZVUK, along with its flow rate, contribute to a somewhat reduced operator hazard on the standard 16.3-in Yugoslavian-pattern AK rifle, when compared to that of the previously evaluated Dead Air Wolverine.  

The signatures measured at the shooter’s ear are presented and analyzed in the full Member Version of this report.

The initial summary from the beginning of the report is repeated below, with more information.

6.202.5 Suppression Rating Comparison (7.62x39mm from the AK Platform)

Figure 6 presents a comparison of the PEW Science Suppression Ratings of the Zastava ZVUK and the Dead Air Wolverine silencers on a full-size Yugoslavian (Serbian) AK-pattern rifle.  The standard PEW Science AK-pattern test host weapon systems are described in Public Research Supplement 6.200.

Figure 6. Suppression Rating Comparisons of Zastava ZVUK and Dead Air Wolverine Using PEW-SOFT 7.62×39mm Supersonic AK Test Data and PEW Science Analysis

From the above 7.62x39mm AK-pattern rifle performance metrics, it can be concluded that these systems can be significantly hazardous to both the operator and bystanders, even when suppressed.  Note the performance metrics presented are only of two silencers.  Further AK-pattern rifle testing and analysis with other silencer models is forthcoming.

Several key observations can be made from the above:

  • Both the ZVUK and Wolverine are tributes to the legacy Soviet PBS system, in gross exterior design envelope. They are also both more advanced than the legacy system. However, the level of advancement between the two modern designs differs. The Dead Air Wolverine uses curved and stepped cone baffles with significant over-bore with no ancillary vent structures, whereas the Zastava ZUK uses a monolithic printed design possessing stepped baffles combined with Purposely Induced Porosity (PIP), along with early blast chamber venting and secondary flow paths.  These design differences result in significantly higher pure suppression performance from the ZVUK, with a higher gross flow rate.  The following systems exhibit similar risk to bystanders to the ZVUK on the Zastava ZPAPM70 7.62x39mm AK-pattern rifle, 1.0 meter left of the silencers’ end caps, in the true free field:

  • The higher flow rate of the ZVUK pays personnel hazard reduction dividends on the full size AK-pattern rifle. As the rifle system has significant dwell time, reduction in early time blast load impulse accumulation in close proximity to the barrel muzzle orifice inside the silencer reduces the effective blast impulse transfer to the piston assembly through the barrel gas port. With less piston impulse in early time, the system reciprocation is somewhat delayed, reducing (but not eliminating) the propensity for adverse blast overpressure to impact the operator from the weapon breech.  The suppression performance, 6-in right of the shooter’s right ear, is significantly different between that of the Wolverine and the ZVUK.  However, it should be noted that operator (shooter’s ear) Suppression Ratings below 20, as shown above, are very hazardous.  This is a consequence of silencer muzzle blast suppression (or lack thereof), silencer back pressure exacerbating ejection port blast load hazards, and AK-pattern rifle action noise, which is pervasive during several stages of weapon cycling, as presented in this report.  The Dead Air Wolverine produces the highest operator risk of any published suppressed system in the Standard, on the full size AK rifles.  The Zastava ZVUK produces operator risk on this standard untuned full size Yugoslavian AK rifle that is on par with the following examples:

  • Both systems produce operator risk metrics that are lower than typically desirable on a standard reciprocating suppressed centerfire rifle system. As more silencer models are evaluated on the AK-platform, the gross and localized suppression performance potentials of the platform will be explored.

PEW Science Research Note 11: The Soviet AK-pattern rifle family may be suppressed by a variety of rifle silencer technologies. While historical precedent exists in aesthetics of design, mount system retention, and other characteristics, it is likely that the demanding (and hazardous) nature of the platform is best suited with advanced technologies to maximize personnel risk reduction.  The Zastava ZVUK performance demonstrated in this report illustrates progress toward that goal, especially compared to the previously evaluated Wolverine silencer system.  The Zastava ZVUK is a hybrid design utilizing PIP.  The reader is encouraged to review the technical performance factors associated with PIP technology in past research.  It is anticipated that future evaluations will showcase further performance advancements as technologies progress in development. Furthermore, there may be existing hybrid designs and high flow rate designs that may show promise in balancing blast overpressure suppression and back pressure reduction on AK-pattern systems that may otherwise be relegated to use with traditional AR variants.  This is a subject of future research.

As detailed in this report, signature suppression at the operator’s head is a function of both muzzle and ejection port signatures from AK-pattern weapon systems, as well as action noise components. Specific weapon system parameters, such as dwell time, can significantly influence operator risk.

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.

6.202.6 Review Summary: Zastava ZVUK on the Zastava ZPAPM70 7.62x39mm AK-Pattern Rifle with 16.3-in Barrel

When paired with the Zastava ZPAPM70 and fired with Hornady American Gunner 123gr 7.62x39mm ammunition, the Zastava ZVUK achieved a Suppression Rating™ of 33.7 in PEW Science testing.

As with all weapon systems, the user is encouraged to examine both muzzle and ear Suppression Ratings.

PEW Science Laboratory Staff Opinion:

The Zastava ZVUK is a 3D printed modern tribute to the Soviet Pribor Besshumnoy Stryelbiy (PBS) silencer system.  Unlike the original PBS silencer designs, the ZVUK uses modern technology with a monolithic printed design possessing stepped baffles combined with Purposely Induced Porosity (PIP) under license, along with early blast chamber venting and secondary flow paths.  These design differences result in significant pure suppression performance from the ZVUK and a higher gross flow rate than legacy systems.

Comparison of the ZVUK with the Dead Air Wolverine is necessary and appropriate.  The performance differential between the two silencers is somewhat expected and largely unremarkable when considering the technology generations present in both the silencers. Performance factors of note that bear highlighting are the ZVUK’s lesser impact on weapon kinematics from the reduced back pressure, the lower personnel risk from its more advanced signature suppression of the blast overpressure events, the reduced ejection port blast, and its post-FRP consistency. The Zastava ZVUK is a hybrid design utilizing PIP.  The reader is encouraged to review the technical performance factors associated with PIP technology in past research.

It is also important to note that the FRP produced by the ZVUK is noticeable and persistent. This phenomenon can subject bystanders adjacent to the weapon system to risk that is approximately 40 percent more severe during the first shot compared to subsequent shots, with this silencer on this weapon system.  The Dead Air Wolverine has less severe relative FRP, but every shot from the Wolverine is more severe than even the ZVUK’s FRP.  Further details and performance comparisons of these metrics will be presented in a PEW Science Member Research Supplement for AK-pattern rifles.

Future AK-platform suppression performance publications are forthcoming. For now, relative cross-platform comparisons of bystander and shooter risk are possible with the PEW Science Suppression Rating.  Systems exhibiting similar risk to bystanders to the ZVUK on the Zastava ZPAPM70 7.62x39mm AK-pattern rifle are the HUXWRX (OSS) FLOW 762 Ti on a 10.3-in 5.56 NATO MK18, the YHM Resonator K on an 8-in 300 BLK subsonic bolt-action rifle, the Aero Precision Lahar-30L on a 20-in .308 Bolt-Action Rifle, the Liberty Precision Anthem-S on a 20-in .308 Bolt-Action Rifle, and the Rugged Suppressors Razor762 on an 8-in 300 BLK subsonic bolt-action rifle.  The Zastava ZVUK produces operator risk on this standard untuned full size Yugoslavian AK rifle that is on par with the Surefire SOCOM556-MINI2 with a WARCOMP on a mid-gas 14.5-in 5.56 NATO M4A1, the KAC 556 QDC/MCQ-PRT with 3-Prong or MAMS on a 11.5-in 5.56 NATO SR-15 CQB MOD 2, and the SilencerCo Saker 556 on a 10.3-in 5.56 NATO MK18.

The Zastava ZVUK is HUB mount capable, and includes a direct-thread mount. The user may adapt the silencer to a variety of mounting systems of their preference.

In this review, the Zastava Arms ZVUK performance metrics depend upon suppressing a supersonic centerfire rifle cartridge on an AK-pattern 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 7.62x39mm 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.