SSS.6.130 - Combat Applications Technologies CAT/WB/A1/718 and the M4A1 Mid-Gas 5.56x45mm 14.5-in Barrel Automatic AR15 Rifle
/Combat Application Technologies CAT/WB/A1/718 on the M4A1 Mid-Gas 5.56x45mm AR15 with 14.5-in Barrel
The CAT/WB/A1/718 (“WB” in this report) is designed by Combat Application Technologies (CAT). It is a compact (“K”) 223 caliber centerfire rifle silencer, intended to suppress the 5.56x45mm cartridge, with no barrel length restrictions. It has a 1.6-inch diameter and the silencer core is 5.2 inches long (5.4 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 threaded coupler will result in a total system length of 5.8 inches. The entirety of the silencer is DMLS (3D-printed) from a proprietary Inconel alloy. The factory specified weight of the CAT/WB/A1/718 Inconel core is 12.6 ounces. The CAT/WB/A1 Titanium core model is also available, and weighs 6.9 ounces. Geometry is identical. The third-party flash hider used in testing resulted in a tested system length of approximately 6.1 inches. Both CAT/WB/A1 models 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-CAT-059-001-23. Therefore, data pertaining to the CAT/WB/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 WB mounted with a 3-prong flash hider on the M4A1 Mid-Gas Automatic AR15 rifle, chambered in 5.56x45mm NATO with a 14.5-inch barrel. Federal XM193 55gr ammunition was used in the test. The standard PEW Science M4A1 test host weapon system is described in Public Research Supplement 6.127.
Section 6.130.1 contains the WB test results and analysis.
Section 6.130.2 contains Suppression Rating comparisons of the WB with the SOCOM556-RC2 mounted with the 3-Prong Flash Hider and WARCOMP Closed-Tine Flash Hider.
Section 6.130.3 contains an article summary and PEW Science laboratory staff opinions.
Summary: When paired with the 14.5-in barrel M4A1 and fired with Federal XM193, the CAT/WB/A1/718 achieved a composite Suppression Rating™ of 41.0 in PEW Science testing.
When paired with the 10.3-in barrel MK18 and fired with Federal XM193, the CAT/WB/A1/718 achieved a composite Suppression Rating™ of 35.3 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
6.130.1 CAT/WB/A1/718 Sound Signature Test Results
A summary of the principal Silencer Sound Standard performance metrics of the WB 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/WB/A1/718 Sound Metric Summary
6.130.1.1 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 CAT WB 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/WB/A1/718 5.56x45mm NATO M4A1 Automatic Rifle Muzzle Sound Pressure Signature
Fig 1b. CAT/WB/A1/718 5.56x45mm NATO M4A1 Automatic Rifle Sound Pressure Signature
Figure 2a. CAT/WB/A1/718 5.56x45mm NATO M4A1 Automatic Rifle Muzzle Sound Impulse Signature
Figure 2b. CAT/WB/A1/718 5.56x45mm NATO M4A1 Automatic Rifle Muzzle Sound Impulse Signature
The CAT WB was previously evaluated on the Standard MK18 Weapon System in Review 6.129. In that evaluation, is was noted the holistic performance of the WB on a short barrel 5.56x45mm rifle is similar to that of the CAT ODB (6.120). It was concluded that the CAT SURGE BYPASS technology in the silencers appears to possess performance scaling properties across geometries.
In this evaluation on the Standard M4A1 Weapon System, the above measured signature data indicates that the WB performance does scale with an increase in both barrel length and dwell time. The M4A1 14.5-in barrel mid-length gas system possesses a dwell time significantly longer than that of the MK18 10.3-in barrel carbine-length gas system. The relatively high early time flow rate in the WB, facilitated by its adaptation of the CAT SURGE BYPASS technology, appears to maintain muzzle signature suppression efficacy at lower input pressure, while still preventing weapon over-function on a longer dwell time weapon. High level conclusions of note are:
The CAT WB is producing signatures of comparable consistency on the M4A1 to those it produced on the MK18, while significantly outperforming the Surefire SOCOM556-RC2 (6.128) in pressure attenuation. With the combined expedient pressure blowdown (Figure 1a) and flow consistency (Figure 2a), the pressure attenuation allows the WB to eclipse the muzzle Suppression Rating of the SOCOM556-RC2 by over half a category. Note the gradual rate increase of gas momentum accumulation in Figure 2b, contrasted with the more severe immediate onset measured in the SOCOM556-RC2 test. The WB maintains this behavior from MK18 to M4A1, whereas the SOCOM556-RC2 loses efficiency.
The expedient pressure blowdown from the CAT WB noted above results in the same bolt speed reduction noted in the MK18 test. Not only does the bolt carrier group return to battery later in time than with the SOCOM556-RC2, it impacts the receiver extension later in time. These types of weapon kinematics (the caution in Research Note 3 notwithstanding) are typically noted with high flow rate technologies like HUXWRX Flow-Through but seldom with this degree of muzzle signature suppression. At 40.6, the CAT WB possesses a significant muzzle Suppression Rating on this platform, and it also possesses a 28.7 shooter’s ear Suppression Rating. Hazard reduction performance with the CAT WB is shown to scale from the MK18 to the M4A1, in totality, despite longer dwell time.
It should be noted that the Surefire SOCOM556-RC2 losing efficiency from MK18 to M4A1 is not a typical rifle silencer characteristic. As further testing and analysis with the standard M4A1 host weapon is published by PEW Science in the Silencer Sound Standard research pedigree, further contextual comparisons will be provided.
PEW Science Research Note 1: The first-round-pop (FRP) signature of CAT WB silencer on the 14.5-in barrel M4A1, to bystanders, is extremely minimal, just as on the 10.3-in barrel MK18. The CAT SURGE BYPASS technology is shown to demonstrate significant efficacy in FRP reduction in the 5.56x45mm combustion regimes tested, to date.
PEW Science Research Note 2: 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 80 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 3: The closing time of the AR15 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.
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 4: Note that the muzzle Suppression Rating of the CAT WB is 40.6 and the at-ear Suppression Rating is 28.7; different zones on the Suppression Rating Dose Chart. Despite a relatively high flow rate, the CAT WB still contributes to an ejection port blast signature that increases the overall severity of the signature to the shooter on the standard M4A1 weapon system.
The signatures measured at the shooter’s ear are presented below.
6.130.1.2 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 6-shot test are shown in Figure 4. Again, full and short timescales are shown.
Figure 3a. CAT/WB/A1/718 5.56x45mm NATO M4A1 Automatic Rifle Ear Sound Pressure Signature
Figure 3b. CAT/WB/A1/718 5.56x45mm NATO M4A1 Automatic Rifle Ear Sound Pressure Signature, Short Time Window
Figure 4a. CAT/WB/A1/718 5.56x45mm NATO M4A1 Automatic Rifle Ear Sound Impulse Signature
Figure 4b. CAT/WB/A1/718 5.56x45mm NATO M4A1 Automatic Rifle Ear Sound Impulse Signature Peaks
There are specific differences between the 10.3-in barrel MK18 weapon platform and the 14.5-in barrel M4A1 weapon platform that may significantly influence the hazard to the weapon operator:
Barrel length.
Gas system length.
Gas port size.
The dwell time of the AR15 weapon system (the time required for the bullet to pass the gas port and reach the muzzle to uncork) is a function of factors (1) and (2). The combination of dwell time with factor (3) dictates weapon gas system impulse. Gas system impulse, in combination with barrel shock, dictates overall reciprocation behavior.
PEW Science Research Note 5: The published dataset is currently limited for the M4A1 platform, but distinct comparisons can be made regarding the CAT WB performance and the Surefire SOCOM556-RC2 performance on this platform:
The muzzle signature contribution to operator hazard with the CAT WB is less significant than with the SOCOM556-RC2. The primary blowdown is one clear indicator of this (significant signature decay note, Figure 3b).
The ejection port blast contribution to the operator hazard with the WB is also less severe than with the Surefire silencer. In addition to relatively low pressure amplitude after blowdown, there is only nominally back-loaded FRP impulse accumulation noted (Figure 4b). The CAT WB is producing a more “balanced” signature than the Surefire silencer, to the operator and bystanders on the M4A1, just as it does on the MK18.
As was discussed in the M4A1 Surefire evaluation, two potential factors change the blast load balance at the operator’s head on the M4A1 with the CAT WB, when compared with the CAT WB on the MK18:
Muzzle blast suppression has increased, as well as has standoff from the operator’s head.
There is a propensity for ejection port blast to be more severe due to longer dwell time.
As further M4A1 research is presented by PEW Science, the performance of other silencers on this weapon system will be compared.
6.130.4 Suppression Rating Comparison (5.56x45mm from the M4A1 and MK18)
Figure 5 presents a comparison of the PEW Science Suppression Rating of the CAT WB with the Surefire SOCOM556-RC2 mounted with both the 3-Prong Flash Hider and WARCOMP Closed-Tine Flash Hider mounts on both the M4A1 and MK18 weapon systems. The standard PEW Science M4A1 test host weapon system is described in Public Research Supplement 6.127. The standard PEW Science MK18 test host weapon system is described in Public Research Supplement 6.51.
Figure 5. Suppression Rating Comparisons of the CAT WB and the Surefire SOCOM556-RC2 with different mounts and Host Weapons, Using PEW-SOFT 5.56x45mm Supersonic Test Data and PEW Science Analysis
Figure 5 presents an overall summary of the postulated hazards to the operator and bystanders when fielding the MK18 and M4A1 weapon systems with two different silencers, with one of which using two different muzzle devices. 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 to battery, 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.
The following gross conclusions can be made from the above:
The overall suppression performance of the SOCOM556-RC2 with the 3-Prong Flash Hider Mount does not appreciably increase when lengthening the barrel by 40% over than of the 10.3-in MK18.
Due to the reduced WARCOMP leak severity on the M4A1 system, along with a greater standoff distance between the mount interface and the weapon operator, hazards to both the operator and bystanders with the WARCOMP mount are reduced on the 14.5-in barrel M4A1, when compared to that on the MK18.
The CAT WB provides comparable bystander hazard reduction to the SOCOM556-RC2 3-Prong configuration on the standard MK18, with significantly increased hazard reduction to the weapon operator over that of the Surefire silencer.
The CAT WB provides increased hazard reduction over that of the Surefire silencer to both the operator and bystanders on the M4A1 platform. And, as the CAT WB is a smaller silencer, this conclusion is particularly notable.
As noted in all laboratory evaluations of CAT SURGE BYPASS technology, silencers possessing its design features are able to balance significant muzzle suppression in both supersonic and subsonic ammunition combustion regimes, while balancing both early-time and overall flow rate to produce signatures to operators and bystanders that reduce hazards, while reducing the propensity for weapon over-function. The test data and analysis in this report indicates this also occurs with the CAT WB on this weapon system.
PEW Science Research Note 6: The SURGE BYPASS technology implementation in the WB is slightly different than in the ODB. In the WB A1 implementation of the technology, the staged design has been minimized. PEW Science postulates that the simplification of the the technology in the WB, when compared to that of the ODB, results in more direct performance scaling across 5.56x45mm barrel lengths in both signature suppression and back pressure reduction. MK18 10.3-in barrel evaluation of the WB was presented in 6.129. Further research is needed to characterize other combustion regimes. Regardless of the change in technology implementation between the two silencers, the shorter design envelope of the WB model shows a high degree of performance efficacy across barrel lengths, similar to how the CAT ODB demonstrates “pressure agnostic” behavior in its 5.56x45mm MK18 and subsonic 300 BLK performance envelopes. The ability of silencers to exhibit high performance in a variety of blast load environments (varying both pressure and duration, along with varied shock impulse accumulation with barrel length variation) is relatively uncommon. The Surefire SOCOM556-RC2 (6.52 and 6.128) demonstrates potential challenges with this with varied barrel length, as does the HUXWRX (OSS) HX-QD 762 (6.41 and 6.45) with varied combustion regimes. CGS Hyperion Technology in the Helios QD also demonstrates such pressure-dependent performance variation (albeit variable with muzzle orifice location in that technology). Research is ongoing.
As detailed in this report, the Suppression Rating at the shooter’s ear may be significantly influenced by the ejection port signature from an AR15; 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.
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.
6.130.5 Review Summary: CAT/WB/A1/718 on the M4A1 Mid-Gas 5.56x45mm AR15 with 14.5-in Barrel
When paired with the 14.5-in barrel M4A1 and fired with Federal XM193, the CAT/WB/A1/718 achieved a composite Suppression Rating™ of 41.0 in PEW Science testing.
When paired with the 10.3-in barrel MK18 and fired with Federal XM193, the CAT/WB/A1/718 achieved a composite Suppression Rating™ of 35.3 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/WB/A1/718 (CAT WB) is a compact and extremely advanced 5.56mm machine gun rated rifle silencer that exhibits significant back pressure reduction and sound signature suppression performance, for its size. Its sound suppression performance on both medium and short barrel 5.56x45mm rifles is significant. Notably, the CAT SURGE BYPASS technology in the silencer appears to balance high flow rate behavior with superior overall signature suppression. The silencer is available in two 3D-printed material options; proprietary Inconel alloy and Titanium. The weights of both models are notable. The CAT WB represents one of the most advanced systems evaluated by PEW Science, to date.
This evaluation on the Standard M4A1 Weapon System indicates that the total WB performance envelope scales with an increase in both barrel length and dwell time. The M4A1 14.5-in barrel mid-length gas system possesses a dwell time significantly longer than that of the MK18 10.3-in barrel carbine-length gas system. The relatively high early time flow rate in the WB, facilitated by its adaptation of the CAT SURGE BYPASS technology, appears to maintain muzzle signature suppression efficacy at lower input pressure, while still preventing weapon over-function and minimizing adverse ejection port blast increases on a longer dwell time weapon.
The CAT WB is producing signatures of comparable consistency on the M4A1 to those it produced on the MK18, while significantly outperforming the Surefire SOCOM556-RC2.
The types of weapon kinematics observed with the CAT WB are typically noted with high flow rate technologies like HUXWRX Flow-Through but seldom with this degree of muzzle signature suppression. The CAT WB possesses a significant muzzle Suppression Rating on this platform, and it also possesses a relatively high shooter’s ear Suppression Rating
The SURGE BYPASS technology implementation in the WB is slightly different than in the 7.62mm CAT ODB. In the WB A1 implementation of the technology, the staged design has been minimized. PEW Science postulates that the simplification of the the technology in the WB, when compared to that of the ODB, results in more direct performance scaling across 5.56x45mm barrel lengths in both signature suppression and back pressure reduction. MK18 10.3-in barrel evaluation of the WB was presented in 6.129. Further research is needed to characterize other combustion regimes. Regardless of the change in technology implementation between the two silencers, the shorter design envelope of the WB model shows a high degree of performance efficacy across barrel lengths, similar to how the CAT ODB demonstrates “pressure agnostic” behavior in its 5.56x45mm MK18 and subsonic 300 BLK performance envelopes.
There are specific physical characteristics of the CAT WB that are notable, and may be useful for end users to consider, given the somewhat similar gross free field risk metrics and weapon kinematics to the CAT ODB and HUXWRX FLOW 762 Ti. For example, the factory-specified core weights for the CAT WB are lighter than many competing models, and the length is similar to some “K” silencers. Like the CAT ODB, the WB is available in both Inconel and Titanium versions. The Titanium version of the WB, at a specified core weight of only 6.9 ounces, is extremely light and leaves a significant amount of leeway in mount system weight for users to match the full system weight of a variety of systems. The Inconel version of the WB is 5.7 ounces heavier. Users should note that, in general, the durability and sparking performance of Inconel vs. Titanium silencers may be significant.
In this review, the CAT/WB/A1/718 performance metrics depend upon suppressing a supersonic centerfire rifle cartridge on a commonly fielded 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.
