SSS.6.58 - Rugged Razor and the MK18 5.56x45mm Short Barrel Automatic AR15 Rifle
/Rugged Razor on the MK18 5.56x45mm AR15 with 10.3-in Barrel
The Razor is manufactured by Rugged Suppressors. It is a 30 caliber centerfire rifle silencer, intended to suppress most cartridges with projectiles appropriately sized to travel through the bore, up to and including 300 Remington Ultra Magnum. It has a 1.5-inch diameter and is 6.4 inches in length. Multiple endcap options are available for use with the Razor, including a flash hider endcap and a 5.56 mm endcap. The user may also choose from various Rugged muzzle devices on which to mount the silencer to the host weapon with its welded proprietary dual-taper locking mount. The outer tube and mount are stainless steel and the cast Stellite baffles of the inner core are fully-welded. The silencer weighs 18.6 ounces with the 5.56 mm R3 flash hider. The Razor can be obtained from Silencer Shop.
This Sound Signature Review contains single-test results using the Rugged Razor 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 6.58.1 contains contains the Razor test results and analysis.
Section 6.58.2 contains Suppression Rating comparisons of the Razor with dedicated 5.56 mm bore rifle silencers, including the OSS HX-QD 556, SilencerCo Saker 556, and Surefire SOCOM556-RC2 on the MK18.
Section 6.58.3 contains the review summary and subjective PEW Science opinions.
Note that PEW Science Member Research Supplement 6.59 contains an analysis of the Rugged Razor using the 5.56 mm endcap on the MK18 and compares its performance using the standard 30 caliber endcap.
Summary: When paired with the 10.3-in barrel MK18 and fired with Federal XM193, the Rugged Razor mounted with the R3 flash hider mount achieved a composite Suppression Rating™ of 21.1 in PEW Science testing. As with all weapon systems, the user is encouraged to examine both muzzle and ear Suppression Ratings.
The supersonic .308 performance of the Rugged Razor is detailed in previous Sound Signature Review 6.16, in which it achieved a Suppression Rating of 28.4.
Relative Suppression Rating Performance is Summarized in SSS.7 - PEW Science Rankings
6.58.1 Rugged Razor Sound Signature Test Results
A summary of the principal Silencer Sound Standard performance metrics of the Razor tested with the R3 flash hider mount 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. Rugged Razor Sound Metric Summary
6.58.1.1 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 dataset and bolt-closing signatures. The waveforms are not averaged, decimated, or filtered. The data acquisition rate used in all PEW Science testing is 1.0 MS/s (1 MHz). The peaks, shape, and time phasing (when the peaks occur in relation to absolute time and to each other) of these raw waveforms are the most accurate of any firearm silencer testing publicly available. PEW-SOFT data is acquired by PEW Science independent testing; the industry leader in silencer sound research. For more information, please consult the Silencer Sound Standard.
The primary sound signature pressure histories for all 6 shots with the Razor 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. Rugged Razor 5.56x45mm NATO MK18 Automatic Rifle Muzzle Sound Pressure Signature, 28-AUG-2021
Fig 1b. Rugged Razor 5.56x45mm NATO MK18 Automatic Rifle Sound Pressure Signature, 28-AUG-2021
Figure 2a. Rugged Razor 5.56x45mm NATO MK18 Automatic Rifle Muzzle Sound Impulse Signature, 28-AUG-2021
Figure 2b. Rugged Razor 5.56x45mm NATO MK18 Automatic Rifle Muzzle Sound Impulse Signature, 28-AUG-2021
The Rugged Razor is a 30 caliber rifle silencer, and as such, is significantly over-bored for the 5.56x45mm weapon platform. The excessively large bore diameter, coupled with the relatively low number of baffles (four), results in a relatively high mass flow rate (low back pressure; low PEW Science Omega Metric). The PEW Science Omega Metric for the 5.56x45mm cartridge is the subject of future publication.
The high flow rate of the Razor (a 30 caliber silencer with few baffles) on the 5.56x45mm platform is highlighted by some similarities between the waveforms measured with the Razor and those measured with the OSS HX-QD 556 in Review 6.54. The Razor’s flowrate is not as high as that of the HX-QD 556, but it does exhibit significant initial muzzle blast and bullet exit waveform coupling (Figure 1b) and a relatively fast rate of rise to maximum peak positive phase impulse (Figure 2a).
PEW Science Research Note 1: Although the Razor exhibits some similarities in signature to the HX-QD 556 due to high flow rate, the mechanism by which the Razor achieves its high flow rate is different; a larger axial orifice results in different gas dynamics than the more complex internal geometry of the OSS silencer. Like many rifle silencers, the Rugged Razor relies on the trapping of gas to suppress sound signature. As its bore size increases relative to cartridge diameter, the suppression performance drops; this phenomenon is exacerbated by the relatively low number of baffles and is further evident in the more erratic impulse waveforms (Figure 2). The Rugged Razor is an inefficient short barrel 5.56x45mm silencer, in that its flow rate is measurably lower than that of the OSS HX-QD 556 but its sound suppression performance is also lower. The user may choose to install a 5.56 mm bore endcap in place of the standard 30 caliber endcap on the Rugged Razor. The use of the 5.56 mm endcap changes the gas dynamics, and thus the suppression performance, of the Razor on this platform. This phenomenon is explored in PEW Science Member Research Supplement 6.59.
Significant differences in the the pressure and impulse waveforms shown in Figure 1 and Figure 2, respectively, are noted when compared to those from the Surefire SOCOM556-RC2 in Review 6.52 and the SilencerCo Saker 556 in Review 6.53. As is the case with the OSS HX-QD 556, the gas jetting from the Rugged Razor is significantly faster than observed from the SOCOM556-RC2 and the Saker 556. Distinctive waveform features consistent with low back pressure silencer behavior are discussed above. The Rugged Razor has significantly reduced sound signature suppression performance compared to these dedicated 5.56mm silencers, measured 1.0 m left of the weapon muzzle. However, the performance deficit as measured at the shooter’s-ear on the MK18 host weapon platform is not as significant. This is an example of flow restriction (back pressure) influence on system performance.
The Rugged Razor has significantly lower flow restriction (back pressure) than the Surefire SOCOM556-RC2 and the SilencerCo Saker 556. Omega metric data for the 5.56x45mm cartridge is the subject of ongoing PEW Science research. The measured first-round-pop (FRP) is visible in both the pressure and impulse regimes, in peak amplitude, timing, and wave shape, as is typical from a suppressed rifle. It should be noted that the FRP measured at the muzzle from the Rugged Razor is significant enough that it is noticeable to bystanders, in accordance with PEW Science inner ear response analysis.
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 85 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 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. 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.
Note that the muzzle Suppression Rating of the Rugged Razor is 16.5 and the at-ear Suppression Rating is 18.6; the same zone on the Suppression Rating Dose Chart. The Rugged Razor produces a relatively severe overall signature on this host weapon system; its high flow rate assists with reducing ejection port signature but its muzzle signature is severe enough to increase the overall severity of the signature to the shooter. The use of the 5.56 mm endcap changes the gas dynamics, and thus the suppression performance, of the Razor on this platform. This phenomenon is explored in PEW Science Member Research Supplement 6.59.
6.58.1.2 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 on the left. A zoomed-in timescale is displayed on the right, in a sound pressure region of interest for Shot 1 and Shot 2. The real sound impulse (momentum transfer potential) histories at the ear from the same 6-shot test are shown in Figure 4. Full and short timescales are shown.
Figure 3a. Rugged Razor 5.56x45mm NATO MK18 Automatic Rifle Ear Sound Pressure Signature, 28-AUG-2021
Figure 3b. Rugged Razor 5.56x45mm NATO MK18 Automatic Rifle Ear Sound Pressure Signature, Short Time Window, 28-AUG-2021
Figure 4a. Rugged Razor 5.56x45mm NATO MK18 Automatic Rifle Ear Sound Impulse Signature, 28-AUG-2021
Figure 4b. Rugged Razor 5.56x45mm NATO MK18 Automatic Rifle Ear Sound Impulse Signature Peaks, 28-AUG-2021
Similar to the measurements at the muzzle, the FRP from the Razor at the shooter’s ear is significant enough to be noticeable to the shooter. Also similar to the measurements at the muzzle, there are waveform indicators measured at the ear consistent with low back pressure (low flow restriction; low PEW Science Omega Metric). Though the shape of the impulse waveforms measured at the shooter’s ear share some similarities with those measured with the OSS HX-QD 556, there are erratic features that indicate a less consistent flow rate. PEW Science postulates that this occurs due to the combination of relatively few baffles and large bore size of the Razor for the 5.56x45mm cartridge; the muzzle jetting contribution on the at-ear signature is significant.
When silencers with extremely low back pressure (low flow restriction; low PEW Science Omega Metric) are fired on a centerfire rifle, the blowdown occurs so quickly that late-time waveform features become visible in pressure space. This was highlighted in the review of the OSS HX-QD 762 with 7.62x51mm ammunition from a 20-in bolt action rifle (6.41) and in the review of the OSS HX-QD 556 in (6.54). In this current article examining the Razor, there is a less pronounced decoupling of the ground reflection event from primary muzzle blast. This is due to the slightly higher back pressure of the Rugged Razor when compared to that of the OSS HX-QD 556 on the MK18. It is important to note that the signature from the Rugged Razor will change when using the 5.56 mm endcap instead of the standard 30 caliber endcap. This phenomenon is explored in PEW Science Member Research Supplement 6.59.
Again, the rate of rise to maximum peak positive phase impulse (Figure 4) is consistent with low back pressure (low PEW Science Omega Metric) for the platform. Inner ear response consequences of such low back pressure on the MK18 weapon system are examined in the section below. As discussed in the preceding section, the Rugged Razor is an inefficient short barrel 5.56x45mm silencer, in that its flow rate is measurably lower than that of the OSS HX-QD 556 but its sound suppression performance is also lower. This is highlighted by the significantly lower at-ear Suppression Rating with the Razor than with the HX-QD 556; a consequence of the different mechanism used to increase flow rate (reduce back pressure) with the two silencers.
6.58.2 Suppression Rating Comparison (5.56x45mm from the MK18)
Figure 5 presents a comparison of the PEW Science Suppression Rating of the Rugged Razor to that of the OSS HX-QD 556, the SilencerCo Saker 556, and the Surefire SOCOM556-RC2 with two different mounts on the MK18 automatic AR15 rifle. The standard PEW Science MK18 test host weapon system is described in Public Research Supplement 6.51.
Figure 5. Suppression Rating Comparisons of the Rugged Razor with the OSS HX-QD 556, Saker 556, and SOCOM556-RC2 , Using PEW-SOFT 5.56x45mm Supersonic Test Data
From the above data, it can be concluded that the Rugged Razor, with its 30 caliber bore and few number of baffles, is an inefficient silencer for the MK18 host weapon platform. Although the at-ear Suppression Rating of the Razor is higher than that from the WARCOMP-equipped Surefire SOCOM556-RC2 (6.52) and the SilencerCo Saker 556 (6.53), those two silencer configurations suffer from a mount gas leak and excessive flow restriction (back pressure), respectively. The Razor does not significantly exceed the performance of the Saker 556 at the shooter’s ear on this platform, despite the lower back pressure of the Razor. This is due to the Razor’s severe muzzle signature that coalesces with the ejection port signature on this host weapon platform.
Despite the low PEW Science Back Pressure Metric, Omega of the Rugged Razor with the 5.56x45mm cartridge, its at-ear Suppression Rating is almost a full category lower than that of the OSS HX-QD 556 on the same platform. The performance delta between the two silencers at the muzzle is even more significant. This is due to the differing mechanisms by which the two silencers acheive sound suppression and reduce flow restriction.
Bystanders may perceive the Rugged Razor to be louder than all of the silencers shown in Figure 5 when fired on the MK18 host weapon. Personnel firing the weapon may experience hearing damage risk on par with that from using the SilencerCo Saker 556. It is important to note that the signature from the Rugged Razor will change when using the 5.56 mm endcap instead of the standard 30 caliber endcap. This phenomenon is explored in PEW Science Member Research Supplement 6.59.
The coalescing of the ejection port overpressure with the primary muzzle blast exacerbates the severity of the signature at the shooter’s head position. It is not ejection port signature, alone, that dictates the signature measured at the shooter’s head position. The muzzle signature of the Rugged Razor is loud enough such that the at-ear signature is influenced. This performance factor is significant on a short barrel automatic weapon system (the MK18).
6.58.3 Review Summary: Rugged Razor 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 Rugged Razor mounted with the R3 flash hider mount achieved a composite Suppression Rating™ of 21.1 in PEW Science testing. As with all weapon systems, the user is encouraged to examine both muzzle and ear Suppression Ratings.
PEW Science Subjective Opinion:
The Rugged Razor is a “semi-compact” 30 caliber machine gun rated rifle silencer that possesses moderate sound signature suppression performance with relatively low back pressure. Relative to dedicated 5.56mm bore silencers, it may be considered “full size.” The silencer is advertised to have extreme durability and has a reasonable weight for extreme duty-use silencers of its size, at a total system weight of 18.6 ounces as tested. On the short barrel 5.56x45mm platform, the Razor possesses reduced performance compared with dedicated 5.56mm bore silencers.
The Rugged Razor uses an iteration of a feature-reduced and modified curved-cone baffle, similar to the feature-reduced curved-cone baffle used in the Omega 300 from SilencerCo and other companies. The Razor possesses only four baffles, in an attempt to increase gas flow rate and reduce back pressure. This is in contrast with the method used by similar silencers from Dead Air (the Sandman series) that reduce back pressure by increasing axial orifice area. PEW Science test data indicates that back pressure reduction by increasing flow area may be more efficient for back pressure reduction than reducing the number of baffles for a given cartridge. However, when significantly “over-bored” for a cartridge, sound suppression may decrease in such designs. This example of significant over-bore reducing performance (using a 30 caliber silencer bore on a 5.56 mm host weapon) is reflected in the Suppression Rating in this review. Though a reduction in the number of baffles does save weight, particularly when the baffles are constructed of steel, suppression efficiency is lost. The user may choose to install a 5.56 mm bore endcap in place of the standard 30 caliber endcap on the Rugged Razor. The use of the 5.56 mm endcap changes the gas dynamics, and thus the suppression performance, of the Razor on this platform. This phenomenon is explored in PEW Science Member Research Supplement 6.59.
The dual-taper locking proprietary mount welded to the rear of the Razor that interfaces with Rugged muzzle devices is relatively simple to operate. To install the silencer, the user must thread it onto a coarse-thread mount, which engages a forward taper, and then engage the locking collar which compresses cam levers onto a secondary rear taper. The mount is very secure. PEW Science anecdotal experience with the Rugged mount across various Rugged rifle silencers and host weapons has been overwhelmingly positive and trouble free.
The Rugged Razor is marketed to be durable and is advertised to not have any restrictions on barrel length; therefore, it may be used with aggressive semiautomatic and automatic firing schedules. The combination of durability, small size, and relatively low back pressure compared to that of full-size silencers makes the Razor a reasonable choice for semiautomatic and automatic centerfire rifle use, particularly for cases in which both size and back pressure are a concern.
Users may compare the Razor to the Dead Air Sandman-S due to the similar sizes of the two silencers. It is important to note that the Razor is both shorter and lighter than the Sandman-S. The Razor may be thought of as a silencer with length in-between that of short and “k” silencers. For semi-automatic use cases in which the shooter may be using hearing protection, the Razor may be an attractive alternative due to smaller size and lighter weight, and is very well suited to abnormally severe firing schedules.
In this review, the Razor 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.
