Acta chirurgica Scandinavica. Supplementum
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Acta Chir Scand Suppl · Jan 1982
The behaviour of three standard small calibre projectiles in soap blocks.
A study of three standard small calibre projectiles fired from the ranges of 30 and 100 m against soft soap blocks was performed. The assault rifles used in the tests were the Finnish M 62, the Russian AKM 47 and the American M 16 A 1 with standard ammunition. Impact velocity was measured with photocells and exist velocity with foils. ⋯ At the range of 100 m the stability of the two 7.62 projectiles is almost equal, but the 7.62 AKM 47 projectile released much more of its impact energy to the target. Furthermore, the 5.56 calibre projectile is unstable and goes on showing early tumbling and total break-up behaviour. The ratio between the volumes of cavitation was 1:2:3 (M 62:AKM 47:M 16 A 1).
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Acta Chir Scand Suppl · Jan 1982
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 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.
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The wounding effects of 5.56 and 7.62 mm calibre bullets, hitting on soft tissues of 130 dogs at various velocities ranging from 513 to 933 m/s have been studied. The injury caused by 5.56 mm bullet was more severe than that caused by 7.62 mm bullet. This is due to the difference in ballistic behavior between the two types of bullets. ⋯ Splashing phenomenon could be seen at the exist and the fragments of the bullet could be found somewhere. Based on the comparisons the amount of absorbed energy, the volume of wound channel, the frequency of developing complex wound and the ratio of dimensions between the entrance and the exit, it proved that the injury caused by 5.56 mm bullet was several to dozens of time as severe as that caused by 7.62 mm bullet. Nevertheless, wound extents by both types of bullet would be similar if the inflicting bullet did not show any significant tumbling, breaking or deformation.
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A special type of respiratory distress syndrome has been described in connection with fractures of the long bones, called fat embolism syndrome. In addition to the respiratory signs - tachypnoea, hypoxaemia and snow storm infiltrations in the chest x-ray films- the syndrome consists of petechiae, thrombocytopenia, cerebral disturbances, pyrexia etc. The respiratory insufficiency in this syndrome may be explained by a coagulation disorder, in which the release of tissue thromboplastins from the traumatized tissues results in an interstitial pneumonitis and peripheral thrombocytopenia. ⋯ Cautions handling and early stabilization of fractures reduce the tissue trauma and may thus reduce the manifestations of the fat embolism syndrome. Respiratory assistance is given when necessary, and most often the syndrome is self-resolving. Fulminant cases with increasing symptomatology are treated with methylprednisolone and respirator.
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Acta Chir Scand Suppl · Jan 1979
Break-up behaviour of some small calibre projectiles when penetrating a dense medium.
A study of the break-up patterns of two types of standard ball small calibre bullets fired from a range of 100 meters against targets made of soft soap was performed. A flash X-ray set-up was used to study the behaviour of the bullets while penetrating the soap. ⋯ The longitudinal rotation velocity of the bullets is often so great that this is sufficient to cause-centrifugal stresses of high enough magnitude to cause rupture of the bullet lead core. This in combination with the high retardation forces acting on a bullet penetrating a dense medium at large angles of yaw is sufficient to cause an almost inevitable break-up for fast-tumbling bullets.