Terminal Performance of Lead Free Pistol Bullets in Ballistic Gelatin Using Retarding Force Analysis from High Speed Video
United States Air Force Academy Colorado Springs United States
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Due to concerns about environmental and industrial hazards of lead, a number of military, law enforcement, and wildlife management agencies are giving careful consideration to lead-free ammunition. The goal of lead-free bullets is to gain the advantages of reduced lead use in the environment while maintaining equal or better terminal performance. Accepting reduced terminal performance would foolishly risk the lives of military and law enforcement personnel. This paper uses the established technique of studying bullet impacts in ballistic gelatin to characterize the terminal performance of eight commercial off-the-shelf lead-free handgun bullets for comparison with earlier analysis of jacketed lead bullets. Peak retarding force and energy deposit in calibrated ballistic gelatin are quantified using high speed video. The temporary stretch cavities and permanent wound cavities are also characterized. Two factors tend to reduce the terminal performance of these lead-free projectiles compared to similar jacketed lead designs. First, solid copper construction increase barrel friction, which reduces muzzle velocity and energy, and thus reduces the ability of the bullet to exert damaging forces in tissue simulant. Second, the lower density of copper requires a longer bullet for a given mass and caliber, which reduces remaining powdervolume in the brass cartridge case, which also tends to reduce muzzle velocity and energy. The resultsof the present study are consistent with earlier analysis showing that expansion is necessary to maximize the potential for rapid incapacitation of enemy combatants. In spite of some new non-expanding nose designs that moderately increase forces between bullet and tissue, the largest retarding forces and highest incapacitation potential requires expanding bullets which maximize frontal area.