SSS.8.1.6 - Suppressed Rimfire Pistol Hazards - SilencerCo Sparrow Silencer Hazard Map Brief
/SilencerCo Sparrow on a Beretta 21A Subcompact Semiautomatic Pistol - Hazard Map
This Silencer Hazard Map Brief documents the free field blast overpressure hazards from the SilencerCo Sparrow fielded on the subcompact Beretta 21A semiautomatic pistol firing CCI Standard Velocity 40gr .22LR ammunition from a 2.4-in barrel, as evaluated in technical Report 6.208 and as tabulated in record number 7.1.236 in the Rankings.
The average Suppression Rating hazard contours at 1.6 m silencer end cap elevation from the instrumented blast test computed with the PEW-SOFT HD Blast Hazard Prediction Tool are shown in Figure 1. An animation displaying first-round-pop (FRP) hazard contours and average hazard contours is shown in Figure 2. The Suppression Rating hazard scale is shown in Figure 3. 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.
8.1.6.1 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 is 0.921. The jet stability index during FRP is 0.603.
8.1.6.2 SilencerCo Sparrow Pistol Suppression Hazard Map Observations:
The SilencerCo Sparrow is a full-size 5.08-in long silencer and this evaluation was performed on a subcompact semiautomatic host weapon with subsonic ammunition. Blast load input into the silencer is relatively high, given the 2.4-in barrel length. Blast load output is relatively uncontrolled during FRP and more controlled as the shot string progresses. The average jet stability index indicates focused distal blast load propagation with minimal field spread at close standoff distances, though the index is lower during FRP and the hazard field is more intense. Near-field severity during the first shot is significantly more intense than with most tested rimfire silencers on this platform, though the Sparrow is able to create a relatively uniform risk field in both the forward and rear hemispheres post-FRP. This is a consequence of its simple monocore baffle design which has poor FRP quenching capabilities. Free field hazards of this system are generally considered low to both operators and bystanders, after the first shot. Relative silencer performance, on average, is relatively competitive with modern designs, on this platform.
fig 1. SilencerCo Sparrow Beretta 21A .22LR Free Field Silencer Hazard Map Produced by PEW-SOFT HD Blast Hazard Prediction Tool using PEW Science Test Data
Fig 2. SilencerCo Sparrow Beretta 21A .22LR Free Field Animated Silencer Hazard Map Produced by PEW-SOFT HD Blast Hazard Prediction Tool using PEW Science Test Data
Fig 3. PEW Science Suppression Rating Scale
