SSS.8.1.22 - Suppressed AR-15 Rifle Hazards - Dead Air Lazarus 6 Silencer Hazard Map Brief
/Dead Air Lazarus 6 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 Dead Air Lazarus 6 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 6.225 and as tabulated in record number 7.1.259 in the Rankings. Note that record number 7.1.260 contains direct-thread mount performance data for the Lazarus 6, not represented in this Brief.
The average Suppression Rating hazard contours at 1.6 m silencer end cap elevation from the instrumented blast test of the Lazarus 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.
8.1.22.1 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 0.084.
8.1.22.2 Dead Air Lazarus 6 Suppression Hazard Map Observations:
The Dead Air Lazarus 6 silencer is a hybrid design with high early time flow rate and higher than typical late time flow rate that focuses the blast field forward in a controlled fashion. Blast load input into the silencer is relatively high amplitude from the 10.3-in rifle barrel. Blast load output from the silencer is highly controlled from its distal vent array.
Near-field severity forward of the operator is relatively high and comparable to other high distal flow rate suppressed MK18 systems. Near the operator, risk is somewhat lower due to the lower degree of ejection port blast hazards brought about by the silencer’s lower back pressure. Further hazard reduction may be possible through weapon tuning, though not in an extreme fashion.
The hazard field from the Lazarus 6 system is very consistent, from shot to shot. Blowdown momentum is relatively controlled, post-FRP.
fig 1. Dead Air Lazarus 6 Xeno 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
