Lead round nose bullets can penetrate deeply and strike bone at relatively high velocity and can be cleanly cut in half or shaved vertically. Bone struck by bullets may not only fragment the bone, but also split the bullet. Wood, glass, fabric, plastic, or tissue may leave marks as well as fragments on the bullet tip. The soft exposed lead nose on non-full metal jacketed bullets can be imprinted with anything that is penetrated by the bullet. The above results are uniformly valid only in artificial media (such as ordnance gelatin) but correlate with human tissue. At velocities approaching 1500 fps the bullet is transformed into a rounded ball of lead and copper. This accounts for fragments of copper (with rifling marks) commonly seen as surgical specimens. The jacket stops in the subcutaneous tissue and the bullet will continue to penetrate. An interesting artefact of impacts around 1000 fps is the tendency of the copper jacket to be shed from the lead. Over 1000 fps real expansion starts to occur and by 1200 fps the nose is turned over to form a mushroom shape. Between 8 fps a slight flattening of the bullet nose can be expected. No change in shape occurs until impact velocity achieves about 800 fps. With the exceptions of lung and bone, tissue densities are relatively constant. The degree to which this happens depends upon the texture of the tissue impacted, the velocity at impact, and the softness of the bullet (usually quite constant). Photography will be valuable.Įxpansion of a semi-wadcutter hollowpoint bullet increases the frontal area and blunts the shape. The best surgical pathology description would give dimensions as measured (use vernier calipers for best results), shape, and appearance of surface. Therefore, use caution in opinions regarding the type of weapon or cartridge used based upon examination of bullets. 38 special, and 9 mm parabellum have essentially the same. 30 caliber cartridge developed in 1906 the handgun cartridges called. Most names have a historic basis and have little to do with any real physical measurements: a. Remember in measuring bullets to determine the type of cartridge used that the actual bullet diameter, even of non-deformed bullets, is not the same as the name of the cartridge. (Russell et al, 1995) (Sepehripour et al, 2017) Bullet recovery and handling requires care so that no artefactual deformation of these characteristics occurs. The bullet nose carries information about the target, and recognizing these findings may give a clue to the injury rendered. These spiral lines, or striae, are the result of the gross and microscopic imperfections of the gun from which it was fired and can be as specific as a fingerprint. The bullet sides will bear the markings of the barrel's interior rifling. The bullet base may contain irregular dimples marking the pressure delivered there in its acceleration down the gun barrel. An understanding of the function of a bullet will aid interpretation of morphologic findings. Proceed to Examination of Gunshot Residueįirearms Tutorial menu Criminalistics Laboratory Methods Surgical pathology description of bulletsĮach bullet keeps a diary in its own way of where it has been and what it has done.
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