SSS.8.1.32 - Suppressed AR-18 Rifle Hazards - Apparition Instruments AI 3CM 300 BLK MCX Silencer Hazard Map Brief
/Apparition Instruments AI 3CM on the Sig MCX 300 BLK 6.75-in barrel AR18 Rifle - Hazard Maps
This Silencer Hazard Map Brief documents the free field blast overpressure hazards from the Apparition Instruments AI 3CM silencer in the long and short configuration fielded on the 6.75-in Sig MCX 300 BLK AR-18 Rifle semiautomatic rifle firing Discreet Ballistics 190gr subsonic 300 BLK ammunition, as evaluated in technical Report 6.235 and as tabulated in record numbers 7.1.275 and 7.1.276 in the Rankings, respectively.
The average Suppression Rating hazard contours at 1.6 m silencer end cap elevation from the instrumented blast test of the long configuration of the silencer computed with the PEW-SOFT HD Blast Hazard Prediction Tool are shown in Figure 1. Hazard contours for the short configuration of the silencer are shown in Figure 2. The Suppression Rating hazard scale is shown in Figure 3. 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.
8.1.32.1 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 long configuration of the 3CM is 0.74. The long configuration of the silencer has a lower jet stability index of 0.14.
8.132.2 Apparition Instruments AI 3CM Suppression Hazard Map Observations:
The AI 3CM system is a hybrid design similar in function to the CAT RAT. High early time flow rate reduces back pressure. The long configuration of the silencer produces very controlled jetting resulting in a high degree of hazard reduction in the forward field (Fig. 1). The reduced back pressure elevates operator protection.
When removing the end module, the short configuration of the silencer (Fig. 2) maintains a level of operator protection over that of an unsuppressed system, at the expense of a more hazardous forward field than the long configuration. The higher degree of blast momentum from this very short silencer is reflected in the much lower jet stability index.
Both silencer configurations provide relatively consistent hazard fields after the first shot.
fig 1. Apparition Instruments AI 3CM (Long Configuration) 300 BLK SIG MCX AR-18 Semiautomatic Rifle Free Field Hazard Map Produced by PEW-SOFT HD Blast Hazard Prediction Tool using PEW Science Test Data
fig 2. Apparition Instruments AI 3CM (Short Configuration) 300 BLK SIG MCX AR-18 Semiautomatic Rifle Free Field Hazard Map Produced by PEW-SOFT HD Blast Hazard Prediction Tool using PEW Science Test Data
Fig 3. PEW Science Suppression Rating Scale
