Evaluation of the new type of military bullet and rifling.

The 5.56-mm caliber SS 109 projectile was fired from 7.7'' and 12'' twist rifles, respectively, into soap blocks and porcine thighs at 50-metre range using a standardized experimental setup. For comparison, the effects of the 5.56-mm M 193 bullet fired from the 7.7'' twist barrel and M-16 assault rifle were tested. The volume of residual cavity in soap, the shape and sizes of live tissue wounds, and the mass of surgically debrided devitalized tissue were measured. The effects of the two projectiles at 7.7'' twist were found similar in soap; the SS 109 produced more tissue damage than the M 193 missile. Using the 12" twist rifle, a significant increase in wounding capacity of SS 109 projectile was found. In conclusion, nonsignificant differences in local effects between the two projectiles using the 7.7'' twist rifles were found, and markedly increased effects of the SS 109--12'' system were ascribed to decreased essential stability and its earlier tumbling in penetrating a target. The soap as a live tissue simulant has proven its reliability in testing small-caliber arms.