SSS.8.1.26 - Suppressed AR-15 Rifle Hazards - Tuna Cans 5.56 XL and WRMFZY 5.56 Silencer Hazard Map Brief
/Tuna Cans 5.56 XL and WRMFZY 5.56 on the M4A1 Mid-Gas 5.56x45mm 14.5-in Barrel Automatic AR15 Rifle - Hazard Maps
This Silencer Hazard Map Brief documents the free field blast overpressure hazards from the Tuna Cans 5.56 XL and WRMFZY 5.56 silencers fielded on the 14.5-in M4A1RIII AR-15 semiautomatic rifle firing M193 55gr 5.56 NATO ammunition, as evaluated in technical Report 6.229 and as tabulated in record numbers 7.1.264 and 7.1.265 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 5.56 XL silencer computed with the PEW-SOFT HD Blast Hazard Prediction Tool are shown in Figure 1. Hazard contours for the WRMFZY 5.56 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.
8.1.26.1 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 5.56 XL is 0.47. The Purged version of the silencer has a lower jet stability index of 0.81.
8.126.2 Tuna Cans 5.56 XL and WRMFZY 5.56 Suppression Hazard Map Observations:
Both these Tuna Cans 5.56 silencers are full size; the modular 12-baffle XL model and the monolithic printed model use almost identical baffle technology that produces low early time flow rate and low late time flow rate. Back pressure is high with both models throughout the entire time regime of combustion blowdown. Blast load input into the silencers is relatively high amplitude from the 14.5-in rifle barrel. Blast load output from the silencers is generally controlled after the first shot. Both silencers have significant first round pop (FRP) and stabilize to a high degree post-FRP. with the non-purged model producing a more stable jet. The stability index of the WRMFZY model is higher as a result of a larger degree of early-time volumetric expansion in the silencer. System back pressure is not significantly different between the two silencers.
Near-field severity forward of the operator is generally less intense and less hazardous than many other 5.56 silencers, on average, post-FRP. Both silencers produce relatively hazardous ejection port blast severity near the weapon operator. These hazard fields are highly driven by reduced ejection port blast hazards and may be reduced with weapon tuning.
Both silencer models provide relatively consistent hazard fields after the first shot. Blowdown momentum is significantly controlled after the first shot.
fig 1. Tuna Cans 5.56 XL 14.5-in M4A1 AR-15 Free Field Hazard Map Produced by PEW-SOFT HD Blast Hazard Prediction Tool using PEW Science Test Data
fig 2. Tuna Cans WRMFZY 5.56 14.5-in M4A1 AR-15 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
