12/18/2023 0 Comments Quietest subsonic 300 blackout ammo![]() ![]() The first round pop with subsonic 300 BLK is postulated to be significantly noticeable to bystanders, as determined by PEW Science inner-ear response analysis. PEW Science Note 1: Interestingly, even with the radically high flow rate of the OSS HX-QD 762, Figure 2b shows a slight pressure regime first-round-pop (FRP) and Figure 3 shows a more exaggerated FRP in impulse space. 308, like the Dead Air Sandman-K in Sound Signature Review 6.15. 308 test of this silencer, and other high-flow silencers with. Typically, with longer duration combustion (.308, for example) this reflection coalesces with the continued gas blowdown out of the silencer, as seen in the. This phenomenon is shown in Figure 2a, in which the ground reflection to the sensor is visible at approximately 37 ms. 308, that the sound overpressure decay to ambient happens prior to ground reflection. The flow rate out of the silencer is so fast, and the duration of the smaller subsonic 300 BLK case charge load so much lower than. 308 test analysis, and above, the OSS HX-QD 762 exhibits extremely high flow rate. Again, full and short timescales are shown.Īs discussed in the previous supersonic. The real sound impulse (momentum transfer potential) histories from the same 5-shot test are shown in Figure 3. A zoomed-in timescale displays the region of peak sound pressure in Figure 2b, for the first two shots. The primary sound signature pressure histories for all 5 shots are shown in Figure 2a. In addition to 300 BLK subsonic sound signature comparisons given in Section 6.45.2 of this review, subsonic and supersonic flow comparisons are discussed in Section 6.45.3. This phenomenon is a byproduct of the extremely high flow rate of the silencer, and is discussed later in this article. 308 HX-QD 762 test, the actual sound signature 1.0 m left of the weapon muzzle, as interpreted by the human inner ear in this test, is on-par with that of the. It is extremely important to note that while the overpressure measured 1.0 m left of the muzzle in this subsonic 300 BLK test of the OSS HX-QD 762 is higher than that measured with the same silencer in the supersonic. This extreme event is coupled with the bullet endcap exit, and at a peak of 155.8 dB in Figure 1, is the highest peak sound pressure from a subsonic suppressed weapon system measured by PEW Science, to date. By the time the bullet leaves, the muzzle blast flow is close behind and exits the multi-orifice array in the endcap. ![]() The OSS silencer allows this early time flow to travel relatively unimpeded through the silencer, exiting the endcap prior to the bullet leaving the silencer. Typically, this phenomenon occurs nested with the post-endcap bullet exit event due to flow restriction in silencers trapping this lower pressure volumetric flow in a subsonic flow field. Visibility of plainly decoupled 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 rarely seen in the sound signature of a suppressed small arm weapon system. As always, internal silencer design can significantly influence the measured timing and pressure amplitudes. This is a highly unusual sequence observed when firing subsonic 300 BLK ammunition from a bolt-action weapon system with an attached silencer the precursor flow being plainly visible prior to muzzle blast is a phenomenon resulting from the extremely high flow rate of the OSS technology. The maximum peak pressure amplitude of the first shot the primary muzzle blast flow coupled with the bullet endcap exit event, is measured to be 155.8 dB. Prior to muzzle blast exit, peak precursor flow is measured to reach a peak of 134.9 dB. There are four significant events shown:ĭuring combustion within the weapon system, a 121.1 dB peak is measured.Īs the precursor flow exits the silencer’s endcap vent array, a peak of 128.6 dB is measured. ![]() Figure 1 shows a 2-millisecond long sequence of events during the first test shot with the OSS HX-QD 762, as measured 1.0 m left of the muzzle. ![]()
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