title: Comparison of M-16A2 and M-4 wounding potential.
abstract: OBJECTIVE
  Concerns about altered wounding characteristics of the M-4 carbine have been raised during recent deployments. Using the wound profile method, the purpose of this study was to compare the M-16A2 rifle with the M-4 carbine.
  
  
  METHODS
  The M-4 carbine and M-16A2 rifle were compared by firing five shots each into calibrated 10% ordnance gelatin at a distance of 3 m. Measured parameters included temporary cavity, projectile velocity, penetration depth, and bullet fragmentation.
  
  
  RESULTS
  The M-16A2 rifle produced a higher muzzle velocity (3,155 ft/s vs. 2,848 ft/s; p < 0.001) and larger temporary cavity (15.5 cm vs. 12.5 cm; p = 0.027) but decreased penetration depth (44.7 cm vs. 48.7 cm; p = 0.04), compared with the M-4 carbine.
  
  
  CONCLUSIONS
  The M-16A2 rifle demonstrated greater tissue disruption using the wound profile method, compared with the M-4 carbine. Reduction of the barrel length is the major factor producing the observed phenomena.
authors.affiliation: Department of Orthopaedic Surgery and Rehabilitation, Henry Ford Hospital, Detroit, MI 48202, USA.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Dougherty
authors.forename: Bradford K
authors.initials: BK
authors.lastname: Matthews
mesh_terms: D005145:Face; D005389:Firearms; D005780:Gelatin; D006801:Humans; D008954:Models, Biological; D014948:Wounds, Gunshot