A STUDY OF IGNITION BY RIFLE BULLETS

摘要

Experiments were conducted to examine the potential for rifle bullets to ignite organic matterrnafter impacting a hard surface. The tests were performed using a variety of common cartridgesrn(7.62×51 [.308 Winchester], 7.62×39, 7.62×54R, and 5.56×45 [.223 Remington]) and bullet materialsrn(steel core, lead core, solid copper, steel jacket, and copper jacket). Bullets were fired at a steel platernthat deflected fragments downward into a collection box containing oven-dried peat moss. We foundrnthat bullets could reliably cause ignitions, specifically those containing steel components (core orrnjacket) and those made of solid copper. Lead core-copper jacketed bullets caused one ignition in theserntests. Thermal infra-red video and temperature sensitive paints suggested that the temperature ofrnbullet fragments could exceed 800℃. Bullet fragments collected from a water tank were larger forrnsolid copper and steel core/jacketed bullets than for lead core bullets, which also facilitate ignition.rnPhysical processes are reviewed with the conclusion that kinetic energy of bullets is transformed tornthermal energy by plastic deformation and fracturing of bullets because of the high-strain rates duringrnimpact. Fragments cool rapidly but can ignite organic matter, particularly fine material, if very dryrnand close to the impact site.