SSS.8.1.27 - Suppressed Bolt Action Rifle Hazards - Strategic Sciences MFMD Silencer Hazard Map Brief
/Strategic Sciences MFMD + SDX on a 20-in Barrel .308 Bolt Action Rifle - Hazard Map
This Silencer Hazard Map Brief documents the free field blast overpressure hazards from the Strategic Sciences MFMD + SDX rifle silencer fielded on a 20-in barrel .308 bolt action rifle firing M80 149gr 7.62 NATO ammunition, as evaluated in technical Report 6.230 and as tabulated in record number 7.1.266 in the Rankings.
The average Suppression Rating hazard contours at 1.6 m silencer end cap elevation from the instrumented blast test of the MFMD + SDX silencer computed with the PEW-SOFT HD Blast Hazard Prediction Tool are shown in Figure 1. The Suppression Rating hazard scale is shown in Figure 2. Ground-truth anchored Suppression Ratings from the technical report are annotated 1.0 m left of the end cap (SR_muzzle) and 6 inches right of the shooter’s right ear (SR_ear). Computational parameters and blast overpressure hazard field observations are provided below.
8.1.27.1 PEW-SOFT HD Computational Model Parameters
PEW-SOFT HD code Version 2.2.7 Alpha was used.
Contour elevation is 1.6 m above grade. No reflecting surfaces, other than the ground, are present in the model.
Grid resolution is 0.076 m (3 in).
The average bolt action jet stability index sigma_b of the silencer is 0.27.
8.1.27.2 Strategic Sciences MFMD + SDX Suppression Hazard Map Observations:
The Strategic Sciences MFMD + SDX silencer is a next generation design with an effective length shorter than other high performance silencers due to its over-the-barrel (reflex) installation. With the installed SDX module, it exhibits significant blast load propagation suppression performance with a very high early time flow rate (low early time back pressure) and very low late time flow rate (higher late time back pressure). Blast load input into the silencer is relatively high amplitude from the 20-in rifle barrel. Blast load output from the silencer is relatively controlled, with moderately stable jetting.
Forward field severity is very low compared with that from competing 7.62 NATO systems, and even systems with longer effective lengths. Severity in the rear field near the operator is very low and bolt action weapon system operator hazards are lower for this combustion regime than they are with a semiautomatic weapon system (e.g. SR-25). Forward field dispersion from silencer jetting is relatively controlled for its amplitude as a result of the relatively high Omega Metric (ref. 6.230).
The hazard field from the MFDM + SDX system is very consistent from shot to shot, from the first round onward.
fig 1. Strategic Sciences MFMD + SDX 20-in barrel .308 Bolt-Action Free Field Hazard Map Produced by PEW-SOFT HD Blast Hazard Prediction Tool using PEW Science Test Data
Fig 2. PEW Science Suppression Rating Scale
