Using momentum to determine serious bodily injury: an experimental study using pig eyes

Abstract According to section 2 of the Criminal Code, a firearm is a barrelled weapon that can discharge a projectile capable of causing serious bodily injury or death to a person. Although not defined in the Criminal Code, serious bodily injury has been accepted in Canadian courts as the “penetration or rupture of an eye”. Classifying air guns may be difficult as they are usually not categorized as a firearm, but some are capable of meeting the criteria of a firearm. In previous studies, velocity and/or energy density were used to define a parameter V50, and a minimum energy density range where penetration may occur. This research project sought to evaluate the momentum of the projectile as a new parameter to determine if an air gun is capable of causing serious bodily injury. Three air guns, with five projectile types, were fired 10 times each into pig eyes. Results indicated that a minimum momentum value may be applied to each projectile of a different shape, regardless of the projectile’s mass. Minimum momentum values ranging from 0.026 kg*m/s (pointed) to 0.039 kg m/s (flat nose) were observed. It is hypothesised that impulse, which considers the cross-sectional area of projectiles, would be a universal parameter and more research should be done to test this.