The influence of impact velocity on bullet trajectory deflection through ballistic gelatine.

This paper presents the results of a study on bullet trajectory deflection, for 9 mm Luger Full Metal Jacket Round Nose (FMJ-RN) bullets fired through 23-24 cm of ballistic gelatine. The bullets were fired at different velocities. Impact velocity, energy transfer and bullet trajectory deflection after gelatine perforation were measured and calculated. As was expected, energy transfer to the gelatine blocks generally increased with increasing impact velocity, indicating an altering bullet/gelatine interaction with altering velocity. This alteration did not result in a discernible alteration of bullet trajectory deflection. Deflection angles fell between 5.7° and 7.4° for 136 of the 140 fired shots, with four outliers below 5.7°.

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.

Influence of bullet type and muzzle-to-target distance on trajectory deflection through a soft tissue simulant.

The influence of two different variables on deflection was studied with 9mm Luger calibre bullets, fired through ballistic gelatine. To test whether bullet type affects trajectory deflection, bullets of four different types were fired (20 shots per type) through 25cm of 10% gelatine at a 5m muzzle-to target-distance. A Kruskal-Wallis test showed that the deflection of at least one bullet type was significantly different (p<.001, significance level of 0.05) from the deflection of the other bullet types. To test whether muzzle-to target-distance affects trajectory deflection, additional shots were fired with one of the four bullet types (7.5g FMJ-RN) at 1 and 15m muzzle-to target distances (20 shots per distance), again through 25 cm of 10% gelatine. A Kruskal-Wallis test showed that there was no significant difference (p=.72, significance level of 0.05) in deflection between the three muzzle-to target distances of 1, 5 and 15m.