SSS.8.1.7 - Suppressed AR-15 Rifle Hazards - Stealth Additive Works Tisha Silencer Hazard Map Brief
/Stealth Additive Works Tisha 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 Stealth Additive Works Tisha 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 6.209 and as tabulated in record number 7.1.237 in the Rankings.
The average Suppression Rating hazard contours at 1.6 m silencer end cap elevation from the instrumented blast test of the Tisha 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.
8.1.7.1 PEW-SOFT HD Computational Model Parameters
PEW-SOFT HD code Version 2.2.4 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 0.32.
8.1.7.2 Stealth Additive Works Tisha Suppression Hazard Map Observations:
The Stealth Additive Works Tisha silencer is a compact next generation advanced hybrid design with high early time flow rate and controlled late time flow rate. Blast load input into the silencer is relatively high amplitude from the 10.3-in rifle barrel. Blast load output from the silencer is extremely controlled, with stable jetting, despite the silencer’s multiple vent arrays (both medial and distal).
Near-field severity forward of the operator is extremely low relative to other suppressed MK18 systems. Near the operator, risk increases and is driven by ejection port blast hazards. The early time flow rate from the silencer is high enough such that ejection port blast hazards are reduced. On the untuned MK18 rifle, the Tisha silencer approaches the limits of free field operator risk reduction; further hazard reduction may be possible through weapon tuning.
The hazard field from the Tisha system is consistent, from shot to shot. Blowdown momentum is significantly controlled.
fig 1. Stealth Additive Works Tisha 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
