title: Simulating backspatter of blood from cranial gunshot wounds using pig models.
abstract: Few studies have examined the biomechanical basis for backspatter from cranial gunshot wounds. Backspatter is material which travels against the direction of fire following ejection from a gunshot entrance wound. Our paper focuses on the use of animals for reconstructing this phenomenon. Five live pigs and several slaughtered pigs were shot using either 9 × 19 mm, 115 grain, full metal jacketed ammunition or .22 long rifle, 40 grain, lead, round-nose ammunition. A high-speed camera was used to record the entrance wound formation and backspatter. A small amount of backspattered material was produced with all targets, and blood backspatter was seen in a few cases. However, we conclude that our model provides an understanding of the phenomenon of backspatter and the physical mechanisms associated with it. The various components of the mechanism of backspatter formation are complex and overlap. The principle mechanism observed in pig cranial gunshots was the high-speed impact response of the skin overlying the skull bone. This study has also produced evidence supporting the view that backspatter can result from the splashing of superficial blood if it is already present on the skin. Subcutaneous gas effects have been demonstrated for backspatter from contact shots. There has been no clear evidence of the role of the collapse of a temporary cavity within the brain.
authors.affiliation: University of Otago, PO Box 54, Dunedin, 9054, New Zealand.
authors.forename: G E
authors.initials: GE
authors.lastname: Radford
authors.affiliation: Institute of Environmental Science and Research (ESR), Christchurch Science Centre, 27 Creyke Rd, Christchurch, 8041, New Zealand. michael.taylor@esr.cri.nz.
authors.forename: M C
authors.initials: MC
authors.lastname: Taylor
authors.affiliation: Sir John Walsh Research Institute, Faculty of Dentistry, University of Otago, PO Box 647, Dunedin, 9054, New Zealand.
authors.forename: J A
authors.initials: JA
authors.lastname: Kieser
authors.affiliation: Sir John Walsh Research Institute, Faculty of Dentistry, University of Otago, PO Box 647, Dunedin, 9054, New Zealand.
authors.forename: J N
authors.initials: JN
authors.lastname: Waddell
authors.affiliation: Institute of Environmental Science and Research (ESR), Mount Albert Science Centre, 120 Mount Albert Road, Auckland, 1142, New Zealand.
authors.forename: K A J
authors.initials: KAJ
authors.lastname: Walsh
authors.affiliation: University of Otago, PO Box 54, Dunedin, 9054, New Zealand.
authors.forename: J C
authors.initials: JC
authors.lastname: Schofield
authors.affiliation: Department of Mechanical Engineering, University of Auckland, Auckland, 1010, New Zealand.
authors.forename: R
authors.initials: R
authors.lastname: Das
authors.affiliation: Department of Mechanical Engineering, University of Auckland, Auckland, 1010, New Zealand.
authors.forename: E
authors.initials: E
authors.lastname: Chakravorty
mesh_terms: D000818:Animals; D001801:Blood Stains; D005389:Firearms; D044709:Forensic Ballistics; D020197:Head Injuries, Penetrating / Q000473:pathology*; D023421:Models, Animal; D013552:Swine; D014948:Wounds, Gunshot / Q000473:pathology*
keywords: Backspatter; Ballistics; Cranial gunshot wounds; Pig head