Influence of Muzzle Instability on Bullet Deflection after Perforating Laminated Particleboards

The influence of muzzle instability on bullet deflection, when perforating laminated particleboards, was studied with three different handgun bullet types. The mean deflection angles of .32 Auto FMJ and .38 Special SJHP bullets were calculated to be 0.90° and 0.83°, respectively after perforating particleboards orthogonally at a 1 m muzzle-to-target distance. The mean angles dropped to 0.70° and 0.58° at a 15 m muzzle-to-target distance. The differences in deflection angles proved to be statistically significant (p < 0.05) with p-values of 0.023 and 0.001, respectively. The mean calculated deflection angles of .38 Special LRN bullets also dropped from 1.51° to 1.38° when the muzzle-to-target distance was increased from 1 to 15 m, but this difference was not significant (p-value of 0.357). The results support the hypothesis that muzzle instability has an influence on deflection. The possible implications for shooting incident reconstructions and for future research are discussed.