SSS.6.120 - Combat Application Technologies CAT/ODB/A1/718 and the MK18 5.56x45mm Short Barrel Automatic AR15 Rifle
/Combat Application Technologies CAT/ODB/A1/718 on the MK18 5.56x45mm AR15 with 10.3-in Barrel
The CAT/ODB/A1/718 (“ODB” in this report) is designed by Combat Application Technologies (CAT). It is a 30 caliber centerfire rifle silencer, intended to suppress many cartridges with projectiles appropriately sized to travel through the bore, with no barrel length restrictions. It has a 1.6-inch diameter and the silencer core is 6.8 inches long, including its external flash hiding features. The silencer is HUB compatible (1.375”-24 tpi threading). Therefore, the user may install a variety of 3rd-party mounting systems and muzzle devices with the silencer. Length of the total system will vary, depending on mount choice. For example, use of the CAT/TSF X, a threaded coupler, will result in a total system length of 7.2 inches. However, with the CAT/SPOOKY1 flash hider installed into the CAT/TSF X, the total added length to the end of the flash hider is 5.3 inches. The entirety of the silencer is DMLS (3D-printed) from a proprietary Inconel alloy. The factory specified weight of the CAT/ODB/A1/718 Inconel core is 16.1 ounces. The CAT/ODB/A1 Titanium core model is also available, and weighs 8.7 ounces. Geometry is identical. The third-party flash hider used in testing resulted in a tested system length of approximately 7.5 inches. Both CAT/ODB/A1 models can be obtained from Combat Application Technologies.
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-CAT-059-001-23. Therefore, data pertaining to the CAT/ODB/A1/718 in this Sound Signature Review is published with the express written permission of Combat Application Technologies.
This Sound Signature Review contains single-test results using the ODB mounted with a 3-prong flash hider 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 test. The standard PEW Science MK18 test host weapon system is described in Public Research Supplement 6.51.
Section 6.120.1 contains the ODB test results and analysis.
Section 6.120.2 contains Suppression Rating comparisons of the ODB with dedicated 223 and 30 caliber silencers on the current market, including the 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 6.120.3 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 CAT/ODB/A1/718 achieved a composite Suppression Rating™ of 36.7 in PEW Science testing.
As with all weapon systems, the user is encouraged to examine both muzzle and ear Suppression Ratings.
The supersonic 7.62x51mm and subsonic 300 BLK laboratory performance evaluations of the CAT/ODB/A1/718 are forthcoming.
Relative Suppression Rating Performance is Summarized in SSS.7 - PEW Science Rankings
6.120.1 CAT/ODB/A1/718 Sound Signature Test Results
A summary of the principal Silencer Sound Standard performance metrics of the ODB 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. CAT/ODB/A1/718 Sound Metric Summary
6.120.1.1 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 ODB 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. CAT/ODB/A1/718 5.56x45mm NATO MK18 Automatic Rifle Muzzle Sound Pressure Signature
Fig 1b. CAT/ODB/A1/718 5.56x45mm NATO MK18 Automatic Rifle Sound Pressure Signature
Figure 2a. CAT/ODB/A1/718 5.56x45mm NATO MK18 Automatic Rifle Muzzle Sound Impulse Signature
Figure 2b. CAT/ODB/A1/718 5.56x45mm NATO MK18 Automatic Rifle Muzzle Sound Impulse Signature
The measured signatures from the CAT ODB on this platform indicate atypical behavior. The ODB is a 7.62mm (30 caliber) silencer. However, on the standard MK18 weapon system, the ODB presents signature behavior that, in some ways, mirrors that of dedicated-bore 5.56mm silencers, while sharing other attributes common in signatures generated by so-called Flow Through silencers. Again, this behavior is highly atypical.
The CAT ODB is not a Flow Through silencer; its external muzzle signatures indicate this. However, it demonstrates some similar behavior with other behavior that is grossly different. The following are specific signature features of note measured in this regime, in an atypical combination:
Early combustion signature phenomenology presents as typical (Fig. 1b), along with relatively typical coupling of bullet shock and initial jetting.
The immediate negative phase characterized by consistent rarefaction begins primary jetting with an initial delay (approximately 30 ms, Fig. 1b).
Jet accumulation is linear in early time with minimal first round pop (FRP) divergence.
FRP impulse accumulation (Fig. 2b) is of unusually low amplitude, with a similar rate to that of subsequent shots after initial jetting.
Consistency in impulse accumulation is notable; external flow anomalies are not evident.
Finally, bolt carrier group (BCG) closing signatures, in late time, are significantly delayed (Fig. 1a).
The above external pressure signatures indicate that the CAT ODB is producing the following high-level system behavior. All occur simultaneously:
It possesses the gross muzzle signature suppression characteristics of a high performance dedicated bore 5.56mm silencer on this short barrel weapon system, like a Surefire SOCOM556-RC2 (6.52).
It produces signature consistency with extremely controlled gas momentum, like an Otter Creek Labs Polonium (6.75).
It produces low-amplitude FRP impulse accumulation like a Thunder Beast Dominus (6.105).
Finally, it produces weapon kinematics similar to Flow Through silencers such as the HUXWRX FLOW 556k (6.83) and HUXWRX FLOW 762 Ti (6.114).
The above four behaviors, occurring simultaneously from a 30 caliber silencer on the MK18, are the result of the CAT SURGE BYPASS technology in the ODB.
PEW Science Research Note 1: The SURGE BYPASS technology in the ODB silencers (both Inconel and Titanium versions) consists of multistage pressure reducing regions with multiple stagnation relief zones. Early blast chamber venting to reduce the so-called alpha parameter appears to facilitate the early stage, post-uncorking. It is important to note the differences between so-called Flow Through technology and SURGE BYPASS. In a Flow Through silencer, gas is routed early and continuously through a toroidal overlapping path for final distal exit; heat transfer being a significant performance parameter. With such silencers, the alpha parameter, characterizing internal early time shock propagation and flow rate, is minimized with the externally measured PEW Science Back Pressure Metric, Omega also minimized.
However, in a CAT silencer with SURGE BYPASS technology, while alpha is minimized and managed, the resulting final externally measured Omega Metric may not drop to levels usually seen in a Flow Through silencer. In fact, gross exterior impulse accumulation rates of the CAT ODB, on the MK18, are extremely similar to that of the aforementioned Surefire SOCOM556-RC2 and the Q Trash Panda (6.61).
PEW Science Research Note 2: The measured data in this report illustrates a combination of behaviors never before characterized by the PEW Science laboratory. PEW Science postulates that the SURGE BYPASS technology may represent one of the most significant advancements in semiautomatic rifle silencer technology in the pedigree, to date. For a silencer to possess all of the above mentioned traits on the MK18, simultaneously, is highly atypical, especially for a 30 caliber silencer. No rifle silencer tested by the PEW Science laboratory, to date, let alone a 30 caliber rifle silencer, behaves like the CAT ODB on the MK18.
PEW Science Research Note 3: The FRP signature, to bystanders, from the CAT ODB on the standard MK18 is noticeable but nominal. It is important to note that the ODB is not a dedicated 5.56mm silencer. Though its tested performance is highly advanced for a 30 caliber silencer on the MK18, there are dedicated 5.56mm silencers from CAT.
PEW Science Research Note 4: The holistic suppression performance of the CAT ODB on this weapon system eclipses that of every 30 caliber silencer evaluated to date, including the HUXWRX FLOW 762 Ti, and most 5.56mm silencers on the untuned MK18. This overall conclusion is notable given that the CAT ODB is over-bored for the cartridge. 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). The SURGE BYPASS technology in the CAT ODB produces a performance envelope that is not comparable to these silencers. The closest overall signature competitor, in gross free field bystander and shooter hazard, is the HUXWRX FLOW 762 Ti. It is important to note that when used in environments differing from the free field, the holistic signature differences between Flow Through and SURGE BYPASS may potentially be very significant.
PEW Science Research Note 5: 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 90 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. For a silencer like the ODB to produce these kinematics is atypical. The BCG cycle speed, overall, is much slower than with a typical rifle silencer (with the caveats given in Research Note 6, below. Note that the Member version of this article contains further kinematics discussion).
PEW Science Research Note 6: 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. Weapon function information provided by PEW laboratory personnel is provided in the final section of this article.
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 very 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 7: Note that the muzzle Suppression Rating of the CAT ODB is 35.4 and the at-ear Suppression Rating is 29.5; almost the same zone on the Suppression Rating Dose Chart. Unlike many rifle silencers, the high early time flow rate of the CAT ODB, coupled with its above-average muzzle suppression, is extremely beneficial to the sound signature at the shooter’s ear on the standard MK18 weapon system. The resulting back pressure of the CAT ODB is low, and the muzzle signature is suppressed adequately enough, that the weapon operator is subjected to less significant hearing damage risk. The CAT ODB produces a shooter’s ear Suppression Rating on an untuned MK18 similar to that of silencers such as the HUXWRX FLOW 762 Ti and FLOW 556k in the free field, with a higher degree of bystander suppression. The signatures measured at the shooter’s ear are presented below.
6.120.1.2 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 and 2. 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. CAT/ODB/A1/718 5.56x45mm NATO MK18 Automatic Rifle Ear Sound Pressure Signature
Figure 3b. CAT/ODB/A1/718 5.56x45mm NATO MK18 Automatic Rifle Ear Sound Pressure Signature, Short Time Window
Figure 4a. CAT/ODB/A1/718 5.56x45mm NATO MK18 Automatic Rifle Ear Sound Impulse Signature
Figure 4b. CAT/ODB/A1/718 5.56x45mm NATO MK18 Automatic Rifle Ear Sound Impulse Signature Peaks
The waveforms measured at the shooter’s ear with the CAT ODB on the standard untuned MK18 indicate Flow Through weapon function and signature characteristics with conventional high performance silencer behavior. As discussed in the main section of this report, this is a consequence of the SURGE BYPASS technology in the ODB. The alpha parameter is minimized, without regard to gross Omega Metric. The end result mirrors high flow rate silencer behavior with significant lack of muzzle signature contribution to the operator hazard.
PEW Science Research Note 8: Figure 3b, above, displays Shot 1 and Shot 2 at full time scale. It is important to note the following:
Ground reflection is revealed; this is only possible due to low amplitude blow down at the time regime of interest. This indicates that the nested blowdown and ejection port pulses have diminished to levels of lower hazard, quickly.
Mechanical noise begins to dominate the shooter’s ear signature, early. Note the clear impact of the BCG with the end of the receiver extension prior to forward travel (~50 ms). This event is only visible without significant coalescence of signature from other events; therefore, silencers like the ODB and FLOW series show this phenomenon. Conventional silencers on this weapon system will not. Note that this is one of the reasons testing in the free field is paramount, and one of the reasons the Silencer Sound Standard and MIL-STD require such testing.
The BCG returns to battery in very late time, as previously discussed in Research Note 6. The BCG speed is reduced from typical. For the same bystander Suppression Rating as a Surefire SOCOM556-RC2, the CAT ODB is allowing the weapon to cycle like a HUXWRX FLOW 762 Ti.
The above alludes to weapon kinematics. Signature characteristics expressed in momentum transfer potential (impulse) measured at the operator’s location are displayed in Figure 4. Note that even with its high early time flow rate, the ODB produces post-peak FRP divergence.
PEW Science Research Note 9: As was discussed in the test report of the Maxim Defense DSX SURG (6.111), there are waveform features in Figure 4 pertinent to the behavior of silencers on the standard MK18, in general. The timing and accumulation of FRP impulse, relative to that of other shots, can provide insight into which phenomena are muzzle driven or ejection port driven in an AR15 system, even with limited transducer fielding and measurement points. Typically, with an extremely “low back pressure” silencer, the shooter’s ear signature on the standard MK18 will exhibit front loaded impulse accumulation during FRP; this is because the ejection port pulse is not dominating the signature, so the primary nested FRP accumulation from the muzzle appears earlier in time. With an extremely “high back pressure” silencer, the opposite occurs, with the shooter’s ear signature exhibiting back loaded impulse during FRP on this weapon system. In the case of the HUXWRX FLOW series, the FRP impulse accumulation is nominally balanced. In the case of the CAT ODB SURGE BYPASS system, the FRP impulse still presents as back loaded, but minimally. This illustrates a timing difference in ejection port pulse and muzzle signature coalescence between Flow Through and SURGE BYPASS. SURGE BYPASS results in significantly delayed muzzle blast propagation when compared to that of Flow Through designs, but still possesses extremely high early time flow rate. This is a direct illustration of isolating alpha minimization. This is the only silencer evaluated by this laboratory on the MK18, to date, to exhibit this holistic behavior.
In summary, the CAT ODB, to the shooter, provides an operator experience on the MK18 that is a cross between a Surefire SOCOM556-RC2 and HUXWRX FLOW 762 Ti. That is the most succinct way to describe the holistic signature, gas dynamics, and hazard conditions of the system. It is likely that if the standard MK18 weapon system is tuned, the CAT ODB system will achieve levels of performance not able to be reached by other known systems.
PEW Science Research Note 10: In PEW Science laboratory testing of the ODB, FRP severity differential was completely masked to the weapon operator on the standard MK18, even more so than with the FLOW 762 Ti.
6.120.2 Suppression Rating Comparison (5.56x45mm from the MK18)
Figure 6 presents a comparison of the PEW Science Suppression Rating of the CAT/ODB/A1/718 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 6. Suppression Rating Comparisons of the CAT/ODB/A1/718 and other silencers, Using PEW-SOFT 5.56x45mm Supersonic Test Data and PEW Science Analysis
Figure 6 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.
From the above data, it can be concluded that the CAT ODB exhibits unprecedented performance on the standard untuned MK18 weapon system, especially for a 7.62mm (30 caliber) silencer:
The CAT ODB is over-bored but provides bystander signature severity of the dedicated 5.56mm Surefire SOCOM556-RC2 (6.52), which was designed for the MK18.
The CAT SURGE BYPASS technology in the ODB allows Flow Through-like weapon kinematics and ejection port signature hazard reduction, with the gas momentum control of an Otter Creek Labs Polonium (6.75) which has much higher backpressure.
The above comparisons are with dedicated 5.56mm silencers. If compared to other 30 caliber silencers on the MK18, the CAT ODB performance is in a different regime. The gas dynamics are not comparable; the signature consistency and impulse accumulation rates, alone, indicate such atypical behavior that the PEW Science laboratory postulates SURGE BYPASS technology may create a new performance benchmark in the research pedigree.
PEW Science Research Note 11: Item 3, above, is of particular importance when examining the published Silencer Sound Standard performance pedigree, to date. Traditionally, high flow rate silencers that minimize both the alpha parameter and the Omega Metric encounter performance challenges in the subsonic suppression regime. An excellent example of design change that resulted in significantly reduced performance across generations is the comparison of the legacy Sig Sauer SRD762Ti-QD (6.39) and the Sig Sauer SLH300Ti (6.107). The performance change in that case, due to increased flow rate, may be considered extreme.
Subsonic rifle cartridge suppression, in general, requires a certain amount of gross gas momentum restriction to achieve certain levels of performance. Silencers like the HX-QD and FLOW series from HUXWRX are at an inherent disadvantage in that suppression regime, simply due to their mechanism(s) of action. For a technical explanation of this subsonic regime performance deficiency, the reader is encouraged to examine the subsonic 300 BLK test report of the HUXWRX (OSS) HX-QD 762 (6.45). In that technical white paper, the efficacy of Flow Through technology in the subsonic regime is examined in significant detail. The PEW Science laboratory is performing testing of the CAT ODB in the same subsonic regime, and a technical publication illustrating the performance of SURGE BYPASS with 300 BLK subsonic is forthcoming. Minimization of the alpha parameter to keep early time flow rate high while maintaining a higher Omega Metric, as is done with CAT SURGE BYPASS, pays significant performance dividends in 300 BLK performance.
PEW Science Research Note 12: The CAT ODB, holistically, outperforms most silencers tested on the MK18 by PEW Science, to date, in signature hazard reduction. 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. Therefore, silencers such as the Energetic Armament ARX (6.82), the Rugged Razor762 (6.58), and WARCOMP-equipped Surefire silencers, are postulated to be more hazardous to the unprotected ear than silencers like the CAT ODB. To iterate, the Suppression Rating is a DRC - it is not a subjective quantity; it is an objective quantification of hearing damage risk potential.
As shown in Figure 6, 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.
In summary, the CAT ODB, to the shooter, provides an operator experience on the MK18 that is a cross between a Surefire SOCOM556-RC2 and HUXWRX FLOW 762 Ti. That is the most succinct way to describe the holistic signature, gas dynamics, and hazard conditions of the system. It is likely that if the standard MK18 weapon system is tuned, the CAT ODB system will achieve levels of performance not able to be reached by other known systems. Further laboratory testing is planned.
6.120.3 Review Summary: CAT/ODB/A1/718 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 CAT/ODB/A1/718 achieved a composite Suppression Rating™ of 36.7 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 CAT/ODB/A1/718 (CAT ODB) is a relatively compact and extremely advanced 30 caliber machine gun rated rifle silencer that exhibits significant back pressure reduction and sound signature suppression performance, for its size and caliber designation. Its sound suppression performance on a short barrel 5.56x45mm rifle is significant. Notably, the CAT SURGE BYPASS technology in the silencer appears to balance high flow rate behavior with superior overall signature suppression, even when over-bored for the cartridge. The silencer is available in two 3D-printed material options; proprietary Inconel alloy and Titanium. The weights of both models are notable. The CAT ODB represents one of the most advanced systems evaluated by PEW Science, to date.
The measured test data presented in this white paper indicate that the CAT ODB is producing the following high-level system behavior. All occur simultaneously:
It possesses the gross muzzle signature suppression characteristics of a high performance dedicated bore 5.56mm silencer on this short barrel weapon system, like a Surefire SOCOM556-RC2, with extremely controlled gas momentum, like an Otter Creek Labs Polonium. It produces low-amplitude FRP impulse accumulation like a Thunder Beast Dominus, with weapon kinematics similar to Flow Through silencers such as the HUXWRX FLOW 556k and HUXWRX FLOW 762 Ti. This behavior, occurring simultaneously from a 30 caliber silencer on the MK18, is the result of the CAT SURGE BYPASS technology in the ODB.
The measured data in this report illustrates a combination of behaviors never before characterized by the PEW Science laboratory. PEW Science postulates that the SURGE BYPASS technology may represent one of the most significant advancements in semiautomatic rifle silencer technology in the pedigree, to date. For a silencer to possess all of the above mentioned traits on the MK18, simultaneously, is highly atypical, especially for a 30 caliber silencer. No rifle silencer tested by the PEW Science laboratory, to date, let alone a 30 caliber rifle silencer, behaves like the CAT ODB on the MK18.
Another unusual characteristic of the CAT ODB is that it is offered with so-called HUB universal mount threading at the proximal end. It is not typical for high performance silencers with such technology to use non-proprietary mounts, because mount choice can sometimes significantly influence silencer and suppressed weapon system performance. One unique characteristic of the SURGE BYPASS technology in the CAT ODB is that the alpha parameter minimization is postulated to be robust with mount choice. In other words, different mounting schemes may not adversely influence SURGE BYPASS behavior as much as some other technologies such as Flow Through. Further laboratory evaluations are needed. The presented test data was acquired using a third-party flash hider, for reference.
There are specific comparisons of the CAT ODB with the HUXWRX FLOW 762 Ti that may be useful for end users, given the somewhat similar gross free field risk metrics and weapon kinematics:
The CAT ODB provides even more balanced and high performance on the standard untuned MK18 than the previously evaluated HUXWRX FLOW 762 Ti. While this performance is notable, also notable is the design envelope. The CAT ODB is available in both Inconel and Titanium versions. The Titanium version of the ODB, at a core weight of only 8.7 ounces, leaves 6 ounces of leeway in mount system weight for users to match the full system weight of the FLOW 762 Ti. The CAT/TSF X and CAT/SPOOKY 1 system are 3.75 ounces, total. The Inconel CAT/ODB/A1/718 with that mounting system, is a total of 19.8 ounces. For an Inconel system with the ODB’s performance to be only approximately 5 ounces heavier than the Titanium FLOW 762 Ti system, may be a significant factor for some users. Users should also note that, in general, the durability and sparking performance of Inconel vs. Titanium silencers may be significant.
The PEW Science laboratory has evaluated the Inconel CAT/ODB/A1/718 in complete darkness on short barrel automatic centerfire rifles and semiautomatic 7.62mm rifles with visual, night vision, and thermal observation from the weapon operator. The signatures in all spectra are reduced when compared with identical weapon systems fielded with the HUXWRX FLOW 762 Ti. This performance factor may also be significant for some users.
Finally, another pertinent comparison of the CAT ODB with the HUXWRX FLOW 762 Ti is weapon function. PEW laboratory personnel fielded both silencers on the semiautomatic 7.62mm SCAR 17 weapon system with 13-inch barrel and KNS diSCARder gas regulator. The SCAR weapon system required the same, or greater, gas impulse to reliably cycle with the CAT ODB as with the HUXWRX FLOW 762 Ti. This limited field evaluation indicates that the early time flow rate of the ODB may be extremely similar to that of the FLOW 762 Ti. As stated above, this is unusual due to the external gas dynamics of the ODB. However, this comparison is congruent with the behavior of the two silencers on the 5.56mm MK18, as evidenced by the kinematic data presented in the Member version of this article. Subsonic 300 BLK and supersonic 7.62mm NATO laboratory evaluations of the CAT ODB are forthcoming.
In this review, the CAT/ODB/A1/718 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.
