SSS.6.133 - BOSS Silencers Guillotine and the MK18 5.56x45mm Short Barrel Automatic AR15 Rifle (Free Version)
/BOSS Silencers Guillotine on the MK18 5.56x45mm AR15 with 10.3-in Barrel
The Guillotine is manufactured by Black Ops Suppression Systems (BOSS). It is a 223 caliber centerfire rifle silencer, intended to suppress the 5.56x45mm cartridge on barrel lengths 10.5-in and longer. The Guillotine has a 1.5-inch diameter and is 6 inches long with no mount. The rear of the silencer is threaded with the so-called HUB 1.375”-24tpi threading, allowing the use of a variety of mounting solutions. With the included direct thread mount, the silencer’s length increases to 6.4 inches. The silencer has a Grade 9 Titanium tube and 17-4 heat treated stainless steel baffles, mount, and end cap. The steel model was tested and weighs 11.9 ounces, and the direct thread mount weighs 1.7 ounces, for a total system weight of 13.7 ounces. The Guillotine can be obtained from BOSS Silencers.
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 was funded in part by PEW Science Project PEW-BOSS-067-001-23. Therefore, data pertaining to the Guillotine in this Sound Signature Review is published with the express written permission of Black Ops Suppression Systems.
This Sound Signature Review contains single-test results using the Guillotine mounted with the direct thread mount 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 6.133.1 contains the Guillotine test results and analysis.
Section 6.133.2 contains Suppression Rating comparisons of the Guillotine with dedicated 223 and 30 caliber silencers on the current market, including the CAT WB, PWS BDE 556, CAT ODB, 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 6.133.3 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 BOSS Silencers Guillotine achieved a composite Suppression Rating™ of 32.0 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
6.133.1 BOSS Silencers Guillotine Sound Signature Test Results
A summary of the principal Silencer Sound Standard performance metrics of the Guillotine is shown in Table 1. The data acquired 1.0 m (39.4 in) left of the muzzle is available for viewing to all. The data acquired 0.15 m (6 in) right of the shooter’s ear is only available to membership supporters of PEW Science and the Silencer Sound Standard. You can support public PEW Science testing, research, and development with a membership, here. State-of-the-art public firearm sound signature testing and research conducted by PEW Science is supported by readers like you.
Table 1. BOSS Silencers Guillotine Sound Metric Summary
6.133.1.1 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 Guillotine 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, Shot 3, and Shot 4.
Fig 1a. BOSS Silencers Guillotine 5.56x45mm NATO MK18 Automatic Rifle Muzzle Sound Pressure Signature
Fig 1b. BOSS Silencers Guillotine 5.56x45mm NATO MK18 Automatic Rifle Sound Pressure Signature
Figure 2a. BOSS Silencers Guillotine 5.56x45mm NATO MK18 Automatic Rifle Muzzle Sound Impulse Signature
Figure 2b. BOSS Silencers Guillotine 5.56x45mm NATO MK18 Automatic Rifle Muzzle Sound Impulse Signature
The 5.56mm BOSS Guillotine, like the larger 30-caliber BOSS Chairman (6.132), exhibits significant early time blast jetting, followed by normalized flow (Figure 1b). However, unlike the Chairman in the 7.62mm NATO combustion regime, the Guillotine on the 5.56mm MK18 demonstrates flow normalization throughout the shot string. This is important to note, because both silencers use the same type of internal baffle design; the Guillotine is shorter and the bore aperture is dedicated to the 5.56x45mm cartage.
PEW Science Research Note 1: As described in the aforementioned performance analysis white paper of the BOSS Chairman, the baffle and porting geometry in the primary baffles of the BOSS Guillotine reportedly share some design principles with that of a so-called Tesla Valve; a passive check-valve type geometry. PEW Science has not validated the efficacy of this design principle as applied to centerfire rifle silencer performance. However, it should be noted that because both the Guillotine and the Chairman possess a traditional cone blast baffle that is not ported, early-time shock reflections still contribute to impulse accumulation inside the blast chamber and adjacent to the muzzle interface. It is likely that this early-time blast environment is more influential to weapon function than later time gas phase venting; this conclusion is supported by the kinematics displayed in Figure 1, along with those shown in Section 6.133.1.2. There is a consistent display of increased bolt carrier group speed most likely occurring due to probable early time blast impulse accumulation.
PEW Science Research Note 2: The Guillotine signature somewhat normalizes after Shot 3 on the MK18 (Figure 2b). Even before gas flow normalization, the latent accumulation after the first shot becomes relatively consistent after 31 ms. In the previous study examining the Chairman performance on the 7.62mm NATO platform, it was postulated that combustion propagation inconsistency later in the shot string was potentially a result of pressure stagnation within baffle porting regions of the silencer. In this 5.56mm NATO study of the Guillotine, it is further postulated that the same technology, when further restricted in its primary orifice, may not exhibit such later shot inconsistency or inefficiency. Whether this performance improvement is due to bore restriction in the design, combustion duration, or both, is currently unknown. Further research is needed.
PEW Science Research Note 3: First-round-pop (FRP) performance of the Guillotine on this platform is marginal to bystanders when considering that the first shot is notably less severe than Shot 2. There is also a feature of the silencer’s signature that is pervasive throughout all shots in the string. The early-time jet pulse (30 ms, Figure 1b) moves into rarefaction in every shot, significantly. This is reflected in the gas momentum drop in the impulse accumulation histories shown in Figure 2 at approximately 30.1 ms. After this event, the varied timing of gas propagation results in impulse accumulation that although is not erratic globally, possesses some inconsistencies (Figure 2b). However, gas flow is more consistent than in the case of the aforementioned 7.62mm NATO Chairman evaluation.
On the standard MK18 weapon system, the BOSS Guillotine achieves overall suppression performance that is on-par with that of the Otter Creek Labs Polonium-K (6.95) and SilencerCo Saker 556 (6.53).
PEW Science Research Note 4: 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 75 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 5: 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.
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 6: Note that the muzzle Suppression Rating of the BOSS Guillotine is 31.3 and the at-ear Suppression Rating is 22.0; a lower zone on the Suppression Rating Dose Chart. The somewhat lower flow rate (higher back pressure) of the Guillotine contributes to a more severe ejection port signature, increasing the overall severity of the signature on the standard MK18 weapon system. Weapon tuning may be required to realize the full potential of signature reduction at the operator’s location with this type of silencer. This type of tuning is outside the scope of this article. However, in the study of the Maxim Defense DSX 10.3-in SURG system (6.111), the physics and operational parameters of weapon tuning are examined. Signatures at the shooter’s ear are examined in the Member Version of this review.
6.133.2 Suppression Rating Comparison (5.56x45mm from the MK18)
Figure 6 presents a comparison of the PEW Science Suppression Rating of the BOSS Silencers Guillotine 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 BOSS Silencers Guillotine 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 to 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 BOSS Silencers Guillotine exhibits competitive performance with many other silencers on this platform. On the standard MK18 weapon system, the BOSS Guillotine achieves overall suppression performance that is on-par with that of the Otter Creek Labs Polonium-K (6.95) and SilencerCo Saker 556 (6.53). It eclipses the shooter’s ear performance of the Polonium-K and Saker 556 due to certain blast load duration factors examined in the previous section.
As described in the previous performance analysis white paper of the BOSS Chairman and earlier in this evaluation of the BOSS Guillotine in Research Note 1, the baffle and porting geometry in the primary baffles of these silencers reportedly share some design principles with that of a so-called Tesla Valve; a passive check-valve type geometry. PEW Science has not validated the efficacy of this design principle as applied to centerfire rifle silencer performance. However, it should be noted that the traditional un-ported cone blast baffle may contribute to early-time shock reflections driving impulse accumulation inside the blast chamber and adjacent to the muzzle interface that likely influence weapon function.
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. Weapon tuning with the Guillotine may be recommended to optimize operator hazard reduction.
6.133.3 Review Summary: BOSS Silencers Guillotine 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 BOSS Silencers Guillotine achieved a composite Suppression Rating™ of 32.0 in PEW Science testing.
PEW Science Laboratory Staff Opinion:
The BOSS Silencers Guillotine is a dedicated 5.56 caliber rifle silencer that possesses competitive suppression performance in its size class, in a lightweight envelope. The silencer uses heat treated stainless steel internals with a titanium outer tube, allowing for use on barrels 10.5 inches of length and greater. The BOSS Guillotine, along with its larger 30-caliber sister silencer, the Chairman, possesses a modular rear mounting interface that may be used with a variety of mounting solutions and muzzle devices.
As described in the aforementioned performance analysis white paper of the BOSS Chairman, the baffle and porting geometry in the primary baffles of the BOSS Guillotine reportedly share some design principles with that of a so-called Tesla Valve; a passive check-valve type geometry. PEW Science has not validated the efficacy of this design principle as applied to centerfire rifle silencer performance. However, it should be noted that because both the Guillotine and the Chairman possess a traditional cone blast baffle that is not ported, early-time shock reflections still contribute to impulse accumulation inside the blast chamber and adjacent to the muzzle interface. It is likely that this early-time blast environment is more influential to weapon function than later time gas phase venting in this particular silencer; this conclusion is supported by the kinematics examined in this study. There is a consistent display of increased bolt carrier group speed most likely occurring due to probable early time blast impulse accumulation.
On the standard MK18 weapon system, the BOSS Guillotine achieves overall suppression performance that is on-par with that of the Otter Creek Labs Polonium-K and SilencerCo Saker 556. It eclipses the shooter’s ear performance of the Polonium-K and Saker 556 due to certain blast load duration factors.
The rear mount threading of the BOSS Silencers Guillotine is 1.375”-24tpi; relatively common in many modern rifle silencers. As a result of this common modular interface, a plethora of mounting systems may be used. The performance of the Guillotine may be influenced by mounting system choice. The user’s choice of mount may balance system weight, length, durability, utility, and even back pressure of the silencer. The data presented by PEW Science in this Sound Signature Review was measured with the included direct thread mount.
In this review, the BOSS Guillotine 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.
