SSS.8.1.33 - Suppressed AR-15 Rifle Hazards - Front of Rifle Systems MK12 MOD FOR Silencer Hazard Map Brief
/Front of Rifle Systems MK12 MOD FOR on the M4A1 Mid-Gas 5.56x45mm 14.5-in Barrel Automatic AR15 Rifle - Hazard Maps
This Silencer Hazard Map Brief documents the free field blast overpressure hazards from the Front of Rifle Systems MK12 MOD FOR silencer fielded on the 14.5-in M4A1RIII AR-15 semiautomatic rifle firing M193 55gr 5.56 NATO ammunition, as evaluated in technical Report 6.236 and as tabulated in record number 7.1.277 in the Rankings.
The average Suppression Rating hazard contours at 1.6 m silencer end cap elevation from the instrumented blast test of the MK12 Mod FOR 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 reports 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.
8.1.33.1 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 semiautomatic jet stability index sigma_sa of the silencer is 0.22.
8.1.33.2 Front of Rifle Systems MK12 MOD FOR Reflex silencer Suppression Hazard Map Observations:
The FOR Systems MK12 Mod FOR is a full size reflex hybrid design. To compare overall system length with other non-reflex silencers, an equivalency that may be used is that the MK12 Mod FOR occupies the same resultant length envelope as a standard silencer and mount of approximately 5.6 inches past the barrel shoulder. The MK12 Mod FOR possesses a moderate early-time flow rate and a high late time flow rate. Blast load input into the silencer is relatively high amplitude from the 14.5-in rifle barrel. Blast load output from the silencer is relatively controlled, producing a moderately stable jet.
Near-field severity forward of the operator is somewhat less intense and less hazardous than is the severity near the ejection port of the weapon system. This increased operator hazard is driven by the nature of the over-gassed M4 host, as detailed in the referenced test report.
The silencer provides relatively consistent hazard fields after the first shot with relatively controlled blowdown momentum.
fig 1. Front of Rifle Systems MK12 Mod FOR 14.5-in M4A1 AR-15 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
