SSS.8.1.17 - Suppressed AR-10 Rifle Hazards - AAC 762-SDN-6 Silencer Hazard Map Brief
/AAC 762-SDN-6 on the SR-25 7.62x51mm 14.5-in Barrel Automatic Rifle - Hazard Map
This Silencer Hazard Map Brief documents the free field blast overpressure hazards from the AAC 762-SDN-6 rifle silencer fielded on the 14.5-in KAC SR-25 semiautomatic rifle firing M80 149gr 7.62 NATO ammunition, as evaluated in technical Report 6.220 and as tabulated in record number 7.1.251 in the Rankings.
The average Suppression Rating hazard contours at 1.6 m silencer end cap elevation from the instrumented blast test of the AAC 762-SDN-6 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.
8.1.17.1 PEW-SOFT HD Computational Model Parameters
PEW-SOFT HD code Version 2.2.6 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 0.469.
8.1.17.2 AAC 762-SDN-6 Suppression Hazard Map Observations:
Unlike the legacy version of the silencer, the AAC 762-SDN-6 is a hybrid design with high flow rate, maintaining high performance signature suppression. The silencer controls blast propagation relatively well; blast load input into the silencer is relatively high amplitude from the 14.5-in rifle barrel. Blast load output from the silencer is moderately controlled, with somewhat stable jetting.
Near-field severity forward of the operator is moderate and comparable to many suppressed 5.56 NATO systems of similar barrel lengths. Near the operator, risk increases further and ejection port blast hazards contribute to this increased risk. The early time flow rate from the silencer is high enough such that ejection port blast hazards are reduced to a somewhat greater degree than the previously evaluated Rampart Range Carson 30. The 762-SDN-6 provides similar operator hazard reduction to the CAT AKB on this system. Though further hazard reduction may be possible through weapon tuning, this system evaluation marks the third examination of 7.62 NATO SR-25 testing in the Standard. Further research is ongoing.
The hazard field from the AAC 762-SDN-6 system is consistent, from shot to shot.
fig 1. AAC 762-SDN-6 14.5-in SR-25 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
