SSS.6.221 - AAC 762-SDN-6 and the Q mini FIX 300 BLK Subsonic (Free Version)
/AAC 762-SDN-6 on a Q mini FIX 300 BLK with 8-in Barrel
The 762-SDN-6 is distributed by Advanced Armament Company (AAC). It is a 30 caliber centerfire rifle silencer, intended to suppress most cartridges appropriately sized to travel through the bore. It has an outer diameter that varies from 1.62-in to 1.56-in and the silencer core is 7 inches long with no mount. The silencer may be attached to a variety of weapon systems depending on the user’s choice of mount; in this test program, the silencer was evaluated with its included 1x16 LH HUB mount coupler and accompanying AAC Blackout flash hider. The use of that mounting system with the silencer resulted in a total length of 7.69 inches, as tested. Other mounting options are possible due to the rear of the silencer body being HUB compatible (1.375-24 tpi threading).
The silencer specimen evaluated in this test program is printed titanium. The core of the silencer weighs 10.3 ounces, the HUB mount coupler weighs 1.5 ounces, and the 3-prong Blackout flash hider weighs 2.2 ounces for a total system weight of 14 ounces, as tested. The Inconel production version of the silencer is reported to weigh 20.5 ounces and would therefore weigh approximately 24.2 ounces with the tested HUB coupler and flash hider mount system. The AAC 762-SDN-6 can be obtained from Silencer Shop.
Silencer Hazard Map:
The predicted personnel hazards generated by the tested weapon system in this report, in the free field, are shown in the adjacent Silencer Hazard Map. Click or tap the Map to enlarge. Please reference Silencer Hazard Map Brief 8.1.18 for further details. The PEW-SOFT HD Blast Hazard Prediction Tool and Hazard Mapper is presented in Report 8.1.1.
AAC 762-SDN-6 8-in barrel 300 BLK Subsonic Bolt-Action Free Field Hazard Map Produced by PEW-SOFT HD Blast Hazard Prediction Tool using PEW Science Test Data
Historical Note:
The original 762-SDN-6 was designed and manufactured by the original AAC (Advanced Armament Corporation) and debuted in 2011. The silencer weighed 20 ounces, was 7.66-in long without a mount, had a 1.5-in diameter, and mounted to AAC BLACKOUT 51-tooth ratcheting muzzle devices. The silencer had a fully-welded Inconel baffle stack inside the outer tube. It was intended to be used on cartridges ranging from 7.62 NATO to 5.56 NATO, including 300 AAC Blackout, 6.8 SPC and 6.5. The silencer was the successor to the longer 762-SD which possessed an Inconel blast baffle and stainless steel baffle stack. The materials, performance, and manufacturing methods were considered modern at the time of design and production and significantly influenced the silencer industry state of practice going forward. The new iteration of the silencer evaluated in this report is considerably more advanced than the legacy version of the silencer. Modern high fidelity laboratory evaluation of the legacy 762-SDN-6 is forthcoming.
PEW Science laboratory evaluations of legacy AAC silencers to date include:
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-AAC-137-001-25. Therefore, data pertaining to the 762-SDN-6 in this Sound Signature Review is published with the express written permission of Advanced Armament Company.
This Sound Signature Review contains single-test results using the AAC 762-SDN-6 and 3-prong Blackout flash hider on the Q mini FIX bolt action pistol, chambered in 300 BLK with an 8-inch barrel. Discreet Ballistics 190gr ammunition was used in the test.
Section 6.221.1 contains the AAC 762-SDN-6 test results and analysis.
Section 6.221.2 contains Suppression Rating comparisons with selected .30 rifle silencers in the subsonic 300 BLK ammunition combustion regime.
Section 6.221.3 contains the review summary and PEW Science laboratory staff technical opinions.
Summary: When paired with the Q mini FIX 8-in 300 BLK and fired with Discreet Ballistics 190gr Subsonic Target ammunition, the AAC 762-SDN-6 with its 3-prong Blackout flash hider mount achieved a composite Suppression Rating™ of 68.9 in PEW Science testing.
The 14.5-in barrel KAC SR-25 supersonic .308 performance of the AAC 762-SDN-6 with a direct-thread mount system is detailed in Sound Signature Review 6.220, in which it achieved a composite Suppression Rating of 33.5.
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.
6.221.1 AAC 762-SDN-6 Sound Signature Test Results
A summary of the principal Silencer Sound Standard performance metrics of the AAC 762-SDN-6 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. AAC 762-SDN-6 Sound Metric Summary
6.221.1.1 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 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 5 shots are shown in Figure 1a. A zoomed-in timescale displays the region of peak sound pressure in Figure 1b, for the first three shots. 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. AAC 762-SDN-6 Bolt Action 300 BLK Muzzle Sound Pressure Signature
Fig 1b. AAC 762-SDN-6 Bolt Action 300 BLK Muzzle Sound Pressure Signature, Short Time Window
Figure 2a. AAC 762-SDN-6 Bolt Action 300 BLK Muzzle Sound Impulse Signature
Figure 2b. AAC 762-SDN-6 Bolt Action 300 BLK Muzzle Sound Impulse Signature
This report summarizes the low pressure subsonic 300 BLK testing of the new modern iteration of the AAC 762-SDN-6. The silencer has also been evaluated on the 14.5-in barrel SR-25 with supersonic 7.62 NATO ammunition (6.220).
The AAC 762-SDN-6 demonstrated its high performance supersonic ammunition suppression and high flow rate on the short barrel .308 weapon in the aforementioned test program. In this 300 BLK subsonic test program, the 762-SDN-6 was found to exhibit somewhat unusual behavior. Despite its high flow rate, its subsonic ammunition suppression performance is extremely significant, not only for its size, but in general, when compared to other silencers evaluated on this weapon system. In addition to its combined high flow rate and high gross suppression performance, its first-round-pop (FRP) is observed to be negligible. This is highly unusual.
PEW Science Research Note 1: As previously discussed in the 14.5-in SR-25 evaluation, the internal design of the AAC 762-SDN-6 is staged; it is important to note that the first expansion (blast) chamber of the silencer possesses non-standard surface topology on the first reflector, and similar 3D-printed geometry continues throughout the remainder of the baffles. The blast chamber also possesses circumferential vents at the end of the blast baffle throat that initiate the first flow stage. Flow rate through the silencer is relatively high in early time and controlled in late time, though the termination of the primary and annular pressure staging with the distal vent array does seem to be efficient for gross flow, as observed in both the previous test data and in the above. In practical terms, this means that the new AAC 762-SDN-6 possesses a high gross flow rate, with low back pressure and yet still exhibits high performance signature suppression in multiple combustion regimes (with high pressure, long duration combustion and low pressure, short duration combustion).
PEW Science Research Note 2: Key performance indicators observed in the above measured blast test data include:
Relatively low amplitude free field blast overpressure with somewhat expedient blowdown (Fig. 1a).
Low amplitude and consistent precursor jetting with a distinct and consistent primary jet through all shots (Fig. 1b and Fig. 2).
FRP divergence presents after the primary jet forms and reaches momentum plateau earlier in time than post-FRP peak accumulations; maximum FRP momentum is throttled.
Post-FRP momentum is extremely consistent through the entire blowdown phase.
Performance observations (1) and (2) are unusual given the fact that the silencer’s flow rate is so high. Observations (3) and (4) are highly unusual for this type of silencer in this combustion regime.
PEW Science Research Note 3: Subsonic 300 BLK suppression performance showcased in the above test observations is relatively uncommon. However, the performance is extremely uncommon from silencers exhibiting this high of a flow rate. As discussed in the previous report (Research Note 4, 6.220), the early time flow rate of the AAC 762-SDN-6 is extremely high. During internal PEW Science testing on semiautomatic weapons using subsonic (low pressure) ammunition, weapon cycling proved difficult in some test scenarios. Further research is ongoing. The AAC 762-SDN-6 has the potential to be one of the highest performing 30 caliber silencers with subsonic 300 BLK ammunition evaluated to date, holistically. If the host weapon will cycle with a particular subsonic ammunition with this silencer installed, it is likely the suppression performance will be relatively high. This holds true for both bystander and operator protection.
PEW Science Research Note 4: The above discussion holds true for semiautomatic host suppression. As it stands, the bolt-action suppression showcased in this report is just as significant. The AAC 762-SDN-6, unlike its legacy predecessor, is not a conventional silencer. It is classified as a hybrid design in the PEW Science research taxonomy. More specifically, the AAC 762-SDN-6 is classified as a staged hybrid. Hybrid design silencers are those in which elements of both conventional and high flow rate silencers are used, coupled with other technology variations and staged elements to provide parametrically varied performance attributes. Such attributes include the ability to reduce early-time shock reflections while significantly altering the rate of proximal and distal venting. These silencers may allow for minimal reciprocating weapon functional influence, while at the same time significantly suppressing signature to the operator and bystanders. Hybrid designs span a large range of the market in both brand and performance in different combustion regimes. There also exist subcategories of this class of silencers that have been shown to demonstrate efficacy in multiple flow regimes. Discussion of these subcategories is outside the scope of this report. Other hybrid designs and staged hybrids include those from Otter Creek Labs, Centurion Arms, PTR, CAT, CGS, SilencerCo, Surefire, updated recent Dead Air models, and others. For an overview of the three primary classes of rifle silencer designs, the reader is encouraged to review PEW Science Research Supplement 6.169 and Research Supplement 6.184.
PEW Science Research Note 5: The FRP suppression performance of the AAC 762-SDN-6 with subsonic 300 BLK ammunition is very high. Bystanders will not be subjected to adverse risk during the first shot, when compared to subsequent shots, even on short barrel weapons.
PEW Science Research Note 6: As a staged hybrid, the AAC 762-SDN-6 is best compared with rifle silencers that behave in similar ways; the 762-SDN-6 is not, for example, a staged “gas trap” like the Anthem and Mach series silencers from Liberty Precision Machine. Two particularly interesting comparisons to the 762-SDN-6 are:
The Combat Application Technologies CAT ODB (6.122). The CAT ODB is also a staged hybrid, and the SURGE BYPASS technology quenches FRP more expediently than most, but not as fast as the 762-SDN-6 in this combustion regime. Also, the AAC silencer provides more distal momentum control; the blast propagation from the 762-SDN-6 is lower amplitude than from the CAT ODB; both silencers have exceptionally high flow rates.
The Otter Creek Labs Infinity (6.185). The Infinity is unable to control FRP to the same degree as the AAC and CAT silencer, but it does combine high flow rate with significant suppression performance when using its solid end cap. The AAC 762-SDN-6 outperforms the Infinity by a full category in most areas of the risk field (ref. Silencer Hazard Map Brief 8.1.18).
In a gross sense the overall “Composite” Suppression Rating of the AAC 762-SDN-6 on this host weapon is 68.9; the fifth highest in the current Rankings. This puts the 762-SDN-6 in the company of much larger silencers like the:
The AAC 762-SDN-6 does not reach the suppression levels of the above four silencers, but it is getting close on this weapon system with regard to personnel protection and it is doing so with a significantly higher flow rate, making it well suited to semiautomatic system use, as well. This performance conclusion is significant.
There are purpose-built subsonic 300 BLK silencers with older technologies that still offer very competitive performance. For example, the Surefire SOCOM300-SPS (6.57) outperforms many silencers in both FRP suppression and overall suppression with subsonic 300 BLK. However, the SOCOM300-SPS has significantly higher back pressure than the AAC 762-SDN-6, is almost 8 inches long, and significantly outperformed by the 762-SDN-6. Silencer technology is advancing, even as legacy designs continue to offer competitive performance. Compromises in some performance areas are being tackled; balanced performance is now being achieved in multiple combustion regimes. This has not always been the case. The reader is encouraged to examine how high flow rate silencers with Flow-Through technology from HUXWRX (OSS) may result in significantly reduced performance with the lower pressure and duration combustion of the subsonic 300 BLK cartridge. This is showcased in the HUXWRX HX-QD 762 300 BLK test report (6.45). This type of performance inefficiency is also examined in the Sig Sauer SLH300Ti 300 BLK test report (6.107). Hybrid technologies from PTR, CAT, Otter Creek Labs, and now AAC, offer users more versatile silencer solutions.
PEW Science Research Note 7: An important comparison of AAC 762-SDN-6 subsonic 300 BLK performance is with that of the Liberty Precision Machine Anthem-S2 QD (6.171). The two silencers have similar overall Composite Suppression Ratings on this host weapon platform. However, the 762-SDN-6 outperforms the slightly longer Anthem-S2 QD in FRP suppression and overall muzzle suppression. The AAC 762-SDN-6 does this with significantly lower back pressure. This is also an interesting performance comparison because of the similarity in performance of the two silencers with supersonic 7.62 NATO suppression.
The AAC 762-SDN-6 shooter’s ear suppression performance is examined in the full Member Version of this report.
Gross comparisons with other silencers in the subsonic 300 BLK combustion regime are shown in Section 6.221.2, below.
6.221.2 Suppression Rating Comparison - Subsonic 300 BLK
The AAC 762-SDN-6 was developed with a focus on high performance sound signature reduction (PEW Science Suppression Rating), with low back pressure in a variety of combustion regimes. As previously discussed, its supersonic and subsonic sound signature suppression performance may be considered high relative to several other systems in the research. Figure 6 shows a performance comparison of many 30 caliber rifle silencer configurations tested with the subsonic 300 BLK cartridge shown in public PEW Science testing, to date. Unsuppressed and suppressed Suppression Ratings are shown for both the shooter and bystanders. The silencers in the figure are shown in no particular order.
Figure 6. Suppression Rating Comparisons Of .30 Rifle Silencers Using PEW-SOFT 300 BLK Subsonic Test Data
Hazards in Figure 6 are expressed with the Suppression Rating; a holistic parameter that captures human inner ear damage risk potential from a measured impulsive complex overpressure signature during the entire time regime of weapon operation, including combustion, complete blowdown, and all mechanical operation, including the carrier group returning to battery (if appliable), in the true free field. The parameter may be used with the dose chart at the beginning of this report. 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. Due to its true free field test data origin and complete waveform analytical calculation basis, it is the only known universal suppressed weapon system signature comparison metric available.
The holistic performance of the AAC 762-SDN-6 with subsonic 300 BLK is relatively close to that of the Liberty Precision Machine Anthem-S2 QD (6.171) and Sig Sauer SRD762Ti-QD (6.39) but outperforms both of those silencers in pure suppression and FRP hazard reduction.
The 762-SDN-6 is very competitive with the CAT ODB (6.122) in operator protection on this weapon system. However, the AAC silencer is able to outperform the ODB in hazard reduction adjacent to the muzzle and in the far field. This performance conclusion is significant, as both silencers have high flow rates and high performance. The 762-SDN-6 also outperforms the CAT ODB in SR-25 suppression, though it may be possible that the CAT ODB outperforms the 762-SDN-6 on 5.56 NATO weapons. Further research is needed.
For silencers 7.7-in length and shorter, the AAC 762-SDN-6 is the highest performing of the group, in this combustion regime. The aforementioned Sig silencer is 8.3 inches long, for example. Only longer silencers are outperforming the 762-SDN-6 with subsonic 300 BLK performance, in current research. With its high flow rate, this performance is extremely notable; none of the longer silencers evaluated have “low back pressure.”
With regard to balancing flow rate with suppression, the reader is encouraged to examine how high flow rate silencers with Flow-Through technology from HUXWRX (OSS) may result in significantly reduced performance with the lower pressure and duration combustion of the subsonic 300 BLK cartridge. This is showcased in the HUXWRX HX-QD 762 300 BLK test report (6.45). This type of performance inefficiency is also examined in the Sig Sauer SLH300Ti 300 BLK test report (6.107). Hybrid technologies from PTR, CAT, Otter Creek Labs, and now AAC, offer users more versatile silencer solutions.
PEW Science Research Note 10: As previously discussed, the new AAC 762-SDN-6 possesses a high gross flow rate, with low back pressure and yet still exhibits high performance signature suppression in multiple combustion regimes (with high pressure, long duration combustion and low pressure, short duration combustion). This is demonstrated both in this report and in the short barrel supersonic 7.62 NATO evaluation of the 762-SDN-6 (6.220). This performance combination is uncommon. It is highly likely, though not yet verified, that the operator protection, and also potentially the bystander protection, showcased by the new AAC 762-SDN-6 is significantly more robust than the higher back pressure legacy 762-SDN-6 on multiple weapon systems. Future research will examine these performance comparisons.
The difference in sound signature suppression performance from silencers in the subsonic 300 BLK suppression regime can be extremely significant. The user is encouraged to be mindful of the degree to which sound signature suppression, and resulting personnel hazards, can vary across designs. Small arm weapon system suppression performance is a spectrum. The PEW Science Suppression Rating and the Silencer Sound Standard help quantify this spectrum for end users and industry, objectively.
6.221.3 Review Summary: AAC 762-SDN-6 on a Q mini FIX 300 BLK with 8-in Barrel
When paired with the Q mini FIX 8-in 300 BLK and fired with Discreet Ballistics 190gr Subsonic Target ammunition, the AAC 762-SDN-6 with its 3-prong Blackout flash hider mount achieved a composite Suppression Rating™ of 68.9 in PEW Science testing.
The 14.5-in barrel KAC SR-25 supersonic .308 performance of the AAC 762-SDN-6 with a direct-thread mount system is detailed in Sound Signature Review 6.220, in which it achieved a composite Suppression Rating of 33.5.
As with all weapon systems, the user is encouraged to examine both muzzle and ear Suppression Ratings.
PEW Science Laboratory Staff Opinion:
The AAC 762-SDN-6 is a midsize 30 caliber rifle silencer with significantly high suppression performance and flow rate. The silencer is an updated modern iteration of the legacy version that originally debuted in 2011. The new silencer is a hybrid design; manufacturing methods have advanced considerably in the fifteen years since the debut of the legacy silencer. Additive manufacturing, silencer combustion testing and analysis, and blast dynamics education have created an environment in which designers may take more efficient advantage of design envelopes. The silencer is roughly the same size as the legacy model and HUB-mount system compatible. The new 762-SDN-6 is constructed from 3D-printed Inconel alloy.
The internal design of the AAC 762-SDN-6 is staged; it is important to note that the first expansion (blast) chamber of the silencer possesses non-standard surface topology on the first reflector, and similar 3D-printed geometry continues throughout the remainder of the baffles. The blast chamber also possesses circumferential vents at the end of the blast baffle throat that initiate the first flow stage. Flow rate through the silencer is relatively high in early time and controlled in late time; the gross flow is very efficient, as observed in the above measured test data. In practical terms, this means that the new AAC 762-SDN-6 has low back pressure and yet still exhibits high performance signature suppression in multiple combustion regimes (with high pressure, long duration combustion and low pressure, short duration combustion). This is demonstrated both in the subject report and in the short barrel supersonic 7.62 NATO evaluation of the 762-SDN-6. This performance combination is uncommon.
The early time flow rate of the AAC 762-SDN-6 is extremely high. During internal PEW Science testing on semiautomatic weapons using subsonic (low pressure) ammunition, weapon cycling proved difficult in some test scenarios. Research is ongoing. For a silencer with that high of a flow rate, its achieved suppression performance is extremely notable.
For silencers 7.7-in length and shorter, the AAC 762-SDN-6 is the highest performing of the group, in this combustion regime. The aforementioned Sig Sauer SRD762QD-Ti silencer is 8.3 inches long, for example. Only longer silencers are outperforming the 762-SDN-6 with subsonic 300 BLK performance, in current research. With its high flow rate, this performance is extremely notable; none of the longer silencers evaluated have “low back pressure.”
It is highly likely, though not yet verified, that the operator protection, and also potentially the bystander protection, showcased by the new AAC 762-SDN-6 is significantly more robust than the higher back pressure legacy 762-SDN-6 on multiple weapon systems. Future research will examine these performance comparisons.
The user may choose to field the Inconel 762-SDN-6 silencer with a variety of mounting systems of their preference. The silencer includes a 1x16 LH HUB mount coupler and accompanying AAC Blackout flash hider. The use of that mounting system with the silencer results in a total length of 7.69 inches.
In this review, the AAC 762-SDN-6 performance metrics depend upon suppressing a subsonic intermediate rifle cartridge. While the sound signature of such cartridges can be suppressed to levels that may result in the desire of the shooter and bystanders to not wear hearing protection, PEW Science encourages the reader to remain vigilant with regard to all subsonic rifle cartridge suppression claims. The gas volume and combustion products created by firing a subsonic intermediate rifle cartridge such as 300 BLK are still significant; the measured pressure and impulse magnitudes, and their durations, illustrate this fact.
The hearing damage potential of subsonic rifle use is not insignificant. PEW Science encourages the reader to consider the Suppression Rating when deciding on an appropriate silencer and host weapon combination for their desired use.
