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Angled shots onto body armour using 9 mm ammunition: the effect on potential blunt injury
  1. Alison Lyall1,
  2. D J Carr1,
  3. C Lankester1 and
  4. C Malbon2
  1. 1Impact and Armour Group, Centre for Defence Engineering, Cranfield University at the Defence Academy of the UK, Shrivenham, UK
  2. 2Mechanical Engineering, Material Science and Civil Engineering, Centre for Applied Science and Technology, Home Office Science, St Albans, Hertfordshire, UK
  1. Correspondence to Dr D J Carr, Impact and Armour Group, Centre for Defence Engineering, Cranfield University at the Defence Academy of the UK, Shrivenham SN6 8LA, UK; d.j.carr{at}


Introduction Some military specialists wear body armour that is more similar to police armour and provides protection from ammunition fired from pistols. During ballistic testing, these armours are mounted on a standardised type of modelling clay and the back face signature (BFS; depth of depression) formed as a result of the non-perforating impact event on to the armour is measured. This study investigated the effect of impact angle on the BFS and on the deformation of the bullet.

Methods Two commonly worn types of armour (HG1/A+KR1 and HG1+KR1) were considered that provide protection from pistol ammunition and sharp weapons. Armours were tested against two types of pistol ammunition (9 mm full metal jacket and 9 mm hollow point) at eight different impact angles (0°, 15°, 30°, 45°, 60°, 70°, 75° and 80°).

Results Increased impact angles resulted in smaller BFSs. Impact angle also affected whether bullets were retained in the armour; as the impact angle increased, the probability of a round exiting the side of the armour increased. Bullet deformation was affected by impact angle.

Conclusions Understanding the deformation of bullets may assist with recreating a shooting incident and interpreting forensic evidence.

  • body armour
  • wounding potential
  • bullet deformation

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  • Contributors CM suggested this study. AL planned and completed this study with assistance from DJC and CL. AL drafted this manuscript from her MSc thesis; DJC, CM and CL commented on the manuscript draft.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement The MSc thesis from which this paper is drafted can be accessed via DJC (