SSS.8.1.36 - Suppressed AR-15 Rifle Hazards - Liberty Precision Machine Torch 762 Silencer Hazard Map Brief
/Liberty Precision Machine Torch 762 on the MK18 5.56x45mm 10.3-in Barrel Automatic AR15 Rifle - Hazard Map
This Silencer Hazard Map Brief documents the free field blast overpressure hazards from the Liberty Precision Machine Torch 762 rifle silencer fielded on the 10.3-in MK18 AR-15 semiautomatic rifle firing M193 55gr 5.56 NATO ammunition, as evaluated in technical Report 6.239 and as tabulated in record number 7.1.280 in the Rankings.
The average Suppression Rating hazard contours at 1.6 m silencer end cap elevation from the instrumented blast test of the Liberty Precision Machine Torch 762 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.
8.1.36.1 PEW-SOFT HD Computational Model Parameters
PEW-SOFT HD code Version 2.2.8 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 0.52.
8.1.36.2 Liberty Precision Machine Torch 762 Suppression Hazard Map Observations:
The Liberty Precision Machine Torch 762 silencer is a .30 caliber rifle silencer that is optimized for small-frame gas gun performance. On the AR-15 platform, its early-time flow rate, consistency, and first-round-pop (FRP) control are all very high. The late time flow rate of the silencer is throttled in this hybrid design which results in a relatively controlled hazard field. Blast load input into the silencer is relatively high amplitude from the 10.3-in rifle barrel. Blast load output from the silencer is stable and produces a balanced risk field from shot to shot.
Near-field severity forward of the operator is moderate to relatively low for the cartridge and weapon. Near the operator, risk is somewhat reduced due to the significant muzzle blast suppression and lower back pressure. The early time flow rate from the silencer is high enough such that ejection port blast hazards are reduced. Further hazard reduction may be possible through weapon tuning.
The hazard field from the Liberty Precision Machine Torch 762 system is very consistent from shot to shot, and that consistency is maintained through the shot string.
fig 1. Blackbird F556 10.3-in MK18 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
