SSS.6.94 - Otter Creek Labs Hydrogen-L and the Q mini FIX 300 BLK Subsonic (Free Version)
/Otter Creek Labs Hydrogen-L on a Q mini FIX 300 BLK with 8-in Barrel
The Hydrogen-L is designed and manufactured by Otter Creek Labs. It is a 30 caliber centerfire rifle silencer, intended to suppress most cartridges with projectiles appropriately sized to travel through the bore, including 300 Remington Ultra Magnum. It has a 1.625-inch diameter and is 9 inches long. The total length with the included direct thread adapter is 9.4 inches. The user may choose to use third-party adapters compatible with the 1.375”-24tpi system. The silencer is tubeless and all welded components are Grade 5 titanium. The silencer weighs 11.9 ounces, and the included direct thread mount weighs 1.9 ounces, for a total system weight of 13.8 ounces, as tested. The Hydrogen-L can be obtained from Otter Creek Labs Dealers.
PEW Science is an independent private testing laboratory and also the world’s only publicly funded suppressed small arms research cooperative. Testing, data analysis, and reporting is generated with funding provided by PEW Science members. Any test data that is generated with any portion of private funding contains this disclosure. The testing and data production for this Sound Signature Review was funded in part by PEW Science Project PEW-OCL-025-001-22. Therefore, data pertaining to the Hydrogen-L in this Sound Signature Review is published with the express written permission of Otter Creek Labs, LLC.
This review contains single-test results using the Hydrogen-L direct-thread mounted to the Q mini FIX bolt action pistol, chambered in 300 BLK with an 8-inch barrel. Discreet Ballistics 190gr ammunition was used in the test.
- Section 6.94.1 contains the Hydrogen-L test results and analysis.
- Section 6.94.2 contains Suppression Rating comparisons with selected .30 rifle silencers in the subsonic flow regime.
- Section 6.94.3 contains Suppression Rating comparisons with selected .30 rifle silencers in both the subsonic and supersonic flow regimes. PEW Science Back Pressure Metric, Ω [Pa-1] comparisons are also included. Further information about the Ω metric and Omega Zones can be obtained in PEW Science Research Supplement 6.40 (Public Article).
- Section 6.94.4 contains the review summary and PEW Science opinions.
Summary: When paired with the Q mini FIX 8” 300 BLK and fired with Discreet Ballistics 190gr Subsonic Target ammunition, the Otter Creek Labs Hydrogen-L in the direct thread configuration achieved a Suppression Rating™ of 70.1 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 Hydrogen-L is detailed in previous Sound Signature Review 6.81, in which it achieved a Suppression Rating of 49.8.
Relative Suppression Rating Performance is Summarized in SSS.7 - PEW Science Rankings
6.94.1 Otter Creek Labs Hydrogen-L Sound Signature Test Results
A summary of the principal Silencer Sound Standard performance metrics of the Otter Creek Labs Hydrogen-L 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 PEW Science testing, research, and development with a membership, here. State-of-the-art firearm sound signature testing and research conducted by PEW Science is supported by readers like you.
Table 1. Otter Creek Labs Hydrogen-L Sound Metric Summary
6.94.1.1 SOUND SIGNATURES AT THE MUZZLE
Real sound pressure histories from a 5-shot test acquired with PEW-SOFT™ are shown below. The waveforms are not averaged, decimated, or filtered. The data acquisition rate used in all PEW Science 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, here.
Figure 1 shows a 6-millisecond long sequence of events during the first test shot with the Otter Creek Labs Hydrogen-L, as measured 1.0 m left of the muzzle. There are five significant events labeled:
During combustion within the weapon system, a 113.4 dB peak is measured.
Precursor flow through the silencer is suppressed, and a peak of 123.4 dB is measured during the initial jetting.
The first major jet peaks at an amplitude of 126.7 dB.
Secondary jetting is measured to be delayed with amplitude as low as 116.3 dB.
Primary jetting results in a peak overpressure amplitude measured to be 131.3 dB, which is the highest of the first shot.
This is a typical sequence observed when firing subsonic 300 BLK ammunition from a bolt-action weapon system with an attached silencer that exhibits high flow restriction (high back pressure); internal silencer design can significantly influence the measured timing and pressure amplitudes. Supersonic and subsonic suppression performance, along with back pressure comparisons are shown in Section 6.94.3 of this review, with the PEW Science Back Pressure Metric, Ω [Pa-1].
Fig. 1 Early-Time Shot History, Otter Creek Labs Hydrogen-L Bolt Action 300 BLK Muzzle Sound Pressure Signature
The back pressure generated by the Otter Creek Labs Hydrogen-L is somewhat similar to, but higher than, both the Diligent Defense Co. Enticer L-Ti (Review 6.88) and the CGS Hyperion (Review 6.71). Its Omega Metric in the supersonic 7.62x51mm flow regime is somewhat lower than that of the Dead Air Nomad-L (Review 6.55). In general, the Hydrogen-L possesses flow restriction (back pressure) higher than that generated by most silencers shown in the published subsonic 300 BLK flow regime by PEW Science, to date. Of the published dataset, the early time flow characteristics of the Hydrogen-L on this weapon system are most similar to that of the CGS Hyperion. This is largely due to the amount of baffles in the Hydrogen-L. It is extremely important to note that the supersonic 7.62x51mm Omega Metric does not scale directly to its 300 BLK counterpart in the subsonic flow regime.
The Hydrogen-L suppression method is best described as brute force in that it utilizes repetitive geometry throughout its copious baffles without significant venting. This method of suppression, with this quantity of baffles, results in significant suppression across flow regimes, as was seen in its supersonic .308 test host data and in the early-time signature of Shot 1 in Figure 1, above. Note the clear delineation of precursor flow, initial primary jetting, and the significantly decoupled secondary jetting onset in which the primary jetting remains suppressed for almost 2 milliseconds. As there are less complex flow paths in the Hydrogen-L than some silencers of its size, this gas dynamics sequence is largely predictable and consistent with its overall geometry, but still notable.
A particularly notable comparison is the muzzle (bystander) signature severity of the Hydrogen-L compared with that of the Sig SRD762Ti-QD (Review 6.39). Their muzzle Suppression Ratings are identical. The Sig silencer has extremely simple geometry, a larger diameter, and a shorter length. The Otter Creek Labs Hydrogen-L is able to outperform the Sig silencer in signature suppression at the shooter’s ear on this host weapon both by exhibiting greater length (standoff) and sound field shape due to lower flow rate.
Unlike the CGS Hyperion, the Hydrogen-L exhibits significant first round pop (FRP) to bystanders on this platform. Quantitative subsonic suppression performance comparisons are provided in Section 6.94.2 of this review.
In a similar fashion to the early time subsonic 300 BLK signature suppression with the aforementioned silencers, precursor flow (the pressure measured from compression and subsequent overpressure pulse through the air column in the gun barrel by the bullet prior to bullet exit) is significantly suppressed. This is in contrast to the subsonic signature generated by silencers with lower flow restriction (lower back pressure). Nonetheless, the primary jetting from ancillary combustion during the first shot is clearly delineated, relative to other shots, below.
The primary sound signature pressure histories for all 5 shots are shown in Figure 2a. A zoomed-in timescale displays the region of peak sound pressure in Figure 2b, for the first three shots. The real sound impulse (momentum transfer potential) histories from the same 5-shot test are shown in Figure 3. Again, full and short timescales are shown.
Fig 2a. Otter Creek Labs Hydrogen-L Bolt Action 300 BLK Muzzle Sound Pressure Signature
Fig 2b. Otter Creek Labs Hydrogen-L Bolt Action 300 BLK Muzzle Sound Pressure Signature, Short Time Window
Figure 3a. Otter Creek Labs Hydrogen-L Bolt Action 300 BLK Muzzle Sound Impulse Signature
Figure 3b. Otter Creek Labs Hydrogen-L Bolt Action 300 BLK Muzzle Sound Impulse Signature
The Otter Creek Labs Hydrogen-L does produce perceptible FRP to bystanders on this platform; it is also easily discernable in both the pressure and impulse regimes (Figure 2 and Figure 3, respectively). Note that the pressure amplitude during Shot 2 and Shot 3 is significantly suppressed, relative to Shot 1 (Figure 2b). The deviation of ancillary early-time combustion behavior during FRP is further highlighted in the impulse regime (Figure 3), in which the first shot reaches peak amplitude at an earlier time than subsequent shots, and with over 98% more peak impulse, on average. Incidentally, the FRP from the Hydrogen-L on this platform may result in hearing damage potential to bystanders that is over 64% more severe during the first shot, than it is during subsequent shots, on average.
PEW Science Research Note 1: While the Hydrogen-L does exhibit relatively high backpressure, its FRP lowers the overall sound suppression performance on this platform. After FRP, the Hydrogen-L produces a significantly suppressed subsonic 300 BLK sound signature to bystanders.
PEW Science Research Note 2: An artifact of the high flow restriction (back pressure) of the Hydrogen-L, relative to the CGS Hyperion for example, is the more gradual impulse accumulation in the muzzle signatures. The reader is encouraged to examine the shape of the initial slopes in Figure 3a of this review and also in Figure 3a in 6.71.1.1. Despite this increase in backpressure, the inner ear response to bystanders from the Hydrogen-L is somewhat more severe than with the Hyperion on this platform.
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.
With subsonic 300 BLK from an 8-inch barrel, the Hydrogen-L is noticeably quieter to bystanders than it is with supersonic .308 from a 20-in barrel. Direct comparisons with other silencers are provided in Section 6.94.2 and 6.94.3, below.
6.94.2 Suppression Rating Comparison - Subsonic 300 BLK
The Otter Creek Labs Hydrogen-L is intended to exhibit extreme sound suppression (exhibiting a high PEW Science Suppression Rating). As previously discussed, its subsonic sound signature suppression performance is high. Figure 6 shows a performance comparison of the 16 .30 rifle silencer configurations tested with the subsonic 300 BLK cartridge shown in public PEW Science testing, to date. Unsuppressed and suppressed Suppression Ratings are shown for both the shooter and bystanders.
Figure 6. Suppression Rating Comparisons Of .30 Rifle Silencers Using PEW-SOFT 300 BLK Subsonic Test Data
The Otter Creek Labs Hydrogen-L is able to significantly restrict gas flow; with its simple baffle geometry used in a large quantity, it is able to match the Suppression Rating at the muzzle of the Sig SRD762Ti-QD (Review 6.39) on this platform. The Hydrogen-L is able to outperform the Sig silencer in signature suppression at the shooter’s ear on this host weapon both by exhibiting greater length (standoff) and sound field shape due to lower flow rate.
The Suppression Rating at the shooter’s ear on this weapon system approaches the 70-zone with extremely quiet 30 caliber rifle silencers. In the currently published dataset, the Hydrogen-L is only bested by the CGS Hyperion (Review 6.71) in this metric.
The propensity of a rifle silencer to exhibit differing sound signature suppression in the supersonic and subsonic flow regimes is typical. To illustrate the differing sound suppression phenomena, summary data for 10 other silencers are presented below.
6.94.3 Suppression Rating Comparison - Subsonic 300 BLK vs. Supersonic .308
The sound suppression performance of eleven silencers in both the supersonic and subsonic flow regimes are compared in Figure 7, below. The solid colors in the plot denote supersonic .308 performance, whereas the typical shaded patterns denote subsonic 300 BLK performance. As the PEW Science Suppression Rating is a universal sound signature metric based upon the response of the human inner ear, all metrics in this plot are comparable to each other, regardless of cartridge. The PEW Science Suppression Rating is the only sound signature metric that allows the comparison of human inner ear response to fast transients, across all suppressed weapon system platforms.
PEW Science has also developed an empirical relation to quantify the back pressure (flow restriction) of silencers. Omega Zones are intended to provide guidance to weapons developers, silencer designers, and end-users, with regard to flow restriction characteristics of different silencer designs. It is very important to note that silencers possessing a relatively high Ω can still provide functional use on weapon systems. Some weapon systems are more sensitive to Ω than others. Note that while the Ω metric is plotted on a linear scale in Figure 7, the parametric relationship is best viewed logarithmically in Research Supplement 6.40. The Omega Metric below is for the .308 Supersonic flow regime.
Figure 7. Suppression Rating Comparisons Of .30 Rifle Silencers Using PEW-SOFT 300 BLK Subsonic and .308 Supersonic Test Data
There is a significant amount of data presented in Figure 7, above. The reader is encouraged to observe the plot legend and notes, such that the data is viewed and interpreted in the appropriate context.
The Hydrogen-L significantly outperforms many silencers in supersonic .308 suppression (Review 6.81). The Hydrogen-L’s flow dynamics are characteristic of Omega Zone 7, similar to that of the Nomad-L. Omega Zone delineation is presented in PEW Science Public Research Supplement 6.40.
High suppression performance in both the supersonic and subsonic flow regimes is atypical for a rifle silencer. Often times, rifle silencers may excel in supersonic suppression performance, with a high flow rate, like the HUXWRX HX-QD 762 (Review 6.41) but suffer in the subsonic flow regime (Review 6.45). Other times, silencers may provide typical performance for their size in the subsonic flow regime, like the Energetic Armament VOX S (Review 6.38), but exhibit primitive design features that diminish supersonic suppression performance (Review 6.3).
Yet another performance compromise is highlighted by silencers like the Silencer Central Banish 30 Gold; a silencer that may perform well, on average, in both flow regimes, but does not exhibit high FRP suppression performance with short 300 BLK barrels; a performance trait that requires more advanced flow dynamics. The CGS Hyperion exhibits class-leading performance in both flow regimes, on average, and with regard to FRP. The Hydrogen-L fits into yet another group. With its more conventional baffle technology, it behaves more like a CGS Hyperion and Dead Air Nomad-L in multiple flow regimes, but maintains some FRP artifacts to bystanders. PEW Science considers the Hydrogen-L to bridge the gap between next-generation silencers and conventional performance in the design envelope.
PEW Science Research Note 5: It is interesting to note that as the Omega Metric increases with certain silencer designs as baffles are added to the stack, suppression does plateau. An excellent case study for the reader is the CGS Hyperion, Nomad-L, and Hydrogen-L; both the Nomad and Hydrogen technology is simply scaled by adding baffles. The Hyperion possesses advanced flow paths early in its geometry that produces a significant vent path during high pressure early-time flow. Even with the Nomad-L’s advanced baffles, simply increasing the number will increase suppression, at the cost of significant back pressure. The Hydrogen-L is no different, in that regard.
PEW Science Research Note 6: Although the peak sound pressure from the Hydrogen-L on this platform is low after FRP, the performance differentials shown in Figure 7 are not only due to peak sound pressure, nor flow rate. Multiple waveform characteristics comprise a silencer’s holistic sound signature. PEW Science postulates that most readers and silencer users have never been presented with information indicating that silencers perform differently in different flow regimes, anecdotal experience notwithstanding. In addition to combustion duration, the time at which peak positive phase pressure is reached, its duration, and its impulse accumulation, are factors that may significantly influence the interpretation of a sound signature by the human ear, and possible hearing damage risk. These phenomena have been demonstrated previously in Section 3 of the OSS, Surefire, and CGS Hyperion K subsonic Sound Signature Reviews.
6.94.4 Review Summary: Otter Creek Labs Hydrogen-L on a Q mini FIX 300 BLK with 8-in Barrel
When paired with the Q mini FIX 8” 300 BLK and fired with Discreet Ballistics 190gr Subsonic Target ammunition, the Otter Creek Labs Hydrogen-L in the direct thread configuration achieved a Suppression Rating™ of 70.1 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 Otter Creek Labs Hydrogen-L is a full-size and lightweight 30 caliber rifle silencer that exhibits very high sound signature suppression performance. The Hydrogen-L is constructed of titanium and has a user-adaptable mounting system. At 13.8 ounces with the direct thread mount, the Hydrogen-L is one of the lightest full size high performance rifle silencers on the current market.
The Hydrogen-L uses a modified stepped cone baffle design in a tubeless welded construction, and does not use porting to an outer annulus. As the silencer is tubeless, this relatively simple geometry allows the Hydrogen-L to exhibit significant weight savings while maintaining adequate strength for magnum rifle cartridges. Despite the simple baffle design, the sound suppression performance of the Hydrogen-L is significant. The high performance of the silencer is due to a combination of the baffle design, their number, and its length. Entering the Composite Suppression Rating 70 Zone on this host weapon, the Hydrogen-L exhibits performance close to that of more complex designs such as the CGS Hyperion, which utilizes more advanced geometry and outer annular space. The Hydrogen-L achieves this performance at the cost of back pressure, due to its design. Nonetheless, the Hydrogen-L bridges the gap between next-generation silencers and conventional performance in the design envelope. It should be noted that the diameter of the silencer is 1.625 inches; the same diameter as the Enticer-L from Diligent Defense.
The rear mount threading of the Hydrogen-L 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 Hydrogen-L 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 direct thread mount.
In this review, the Hydrogen-L performance metrics depend upon suppressing a subsonic intermediate rifle cartridge. While the sound signature of such cartridges can be suppressed to levels that may result in the desire of the shooter and bystanders to not wear hearing protection, PEW Science encourages the reader to remain vigilant with regard to all subsonic rifle cartridge suppression claims. The gas volume and combustion products created by firing a subsonic intermediate rifle cartridge such as 300 BLK are still significant; the measured pressure and impulse magnitudes, and their durations, illustrate this fact.
The hearing damage potential of subsonic rifle use is not insignificant. PEW Science encourages the reader to consider the Suppression Rating when deciding on an appropriate silencer and host weapon combination for their desired use.
