Introduction Terminal performance of a bullet in the human body is critical for the treatment of the wounded person and the optimization of the bullet. The effects of the initial velocity and the initial attack angle of the bullet on the terminal performance needs to be investigated.
Methods Ballistic gelatin was used to simulate the human body. Rigid 7.62 mm rifle bullets were fired into the gelatin blocks. The damaged gelatin was analyzed using the proposed expansion method. Relations between the damaged gelatin and the initial velocity, the initial attack angle were obtained using the fitting method.
Results The damaged gelatin block could be divided into two parts: the less damaged part and the severely damaged part. The length of the less damaged part depends mostly on the initial attack angle. The average damaged area of this part depends on both the initial attack angle and the initial velocity. The cracks contribute significantly to the total volume of damaged gelatin, particularly when the expansion becomes larger than 1.9 mm. The total damaged gelatin increases with the initial velocity, the initial attack angle and the expansion extent. The increasing rate may diminish if the contribution of the cracks to the damaged gelatin is ignored.
Conclusions The expansion method is suitable to investigate the influences of factors of the bullet on the terminal performances. The characteristics of the damaged gelatin have a linear relationship with the initial attack angle and the initial velocity of the bullet.