Mechanisms of development of shot wounds caused by missiles of different initial velocity.
The investigation were carried out on blocks of 20% gelatin. Some of these models contained bones. Shots were fired from a distance of 100 m using bullets of 7.62 mm calibre and 715 m/sec initial velocity and bullets 5.52 mm of about 990 m/sec initial velocity. The illuminated gelatin block was filmed at the time of bullet impact at a rate of 9000 frames/sec. The pressure in the block during passage of the bullet was measured, and the decrease of bullet velocity and kinetic energy per 1 cm of the bullet canal was calculated. The character and size of injury to the block were estimated. After shots with bullets of high velocity following changes were seen as compared to those following the impact of bullets of lower initial velocity; the mean rate of bullet canal widened and the size of the temporary cavity was greater, the cavity decay was longer, and the disturbances in the model persisted longer, the pressure in the blocks reached higher values, the bullet velocity decreased, the diameters of exit wounds and depth of fissures in the blocks were greater, the fissure in the hit bone appeared earlier, the bone fragments were pushed apart at a greater distance and their reapproachment was delayed. The shot through the bone in the block changed all these parameters, and in some cases it produced the phenomenon of three-bubbles development of the temporary cavity. The temporary and permanent changes in the block depended on the mode of bullet impact. Temporary cavity pulsation developed when air was trapped within the block. Bullets of high initial velocity convey their kinetic energy to the hit object through a much greater absolute loss of its velocity producing thus a much greater injury, especially in the second half of the bullet canal, with longer lasting and more extensive temporary changes, and greater permanent changes than in the case of wounds produced with bullets of lower initial velocity.
D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D001842:Bone and Bones / Q000293:injuries; D005780:Gelatin; D008954:Models, Biological; D013552:Swine; D014948:Wounds, Gunshot / Q000473:pathology*
D005780:Gelatin