A Study of Wildfire Ignition by Rifle Bullets

Abstract

Abstract. Experiments were conducted to examine the potential for rifle bullets to ignite organic matter after impacting a hard surface. The tests were performed using a variety of common cartridges (7.62 9 51 [.308 Winchester (The use of tradenames is provided for informational purposes only and does not constitute an endorsement by the U.S. Department of Agriculture.)], 7.62 9 39, 7.62 9 54R, and 5.56 9 45 [.223 Remington]) and bullet materials (steel core, lead core, solid copper, steel jacket, and copper jacket). Bullets were fired at a steel plate that deflected fragments downward into a collection box containing oven-dried peat moss. We found that bullets could reliably cause ignitions, specifically those containing steel components (core or jacket) and those made of solid copper. Lead core-copper jacketed bullets caused one ignition in these tests. Thermal infra-red video and temperature sensitive paints suggested that the temperature of bullet fragments could exceed 800°C. Bullet fragments collected from a water tank were larger for solid copper and steel core/jacketed bullets than for lead core bullets, which also facilitate ignition. Physical processes are reviewed with the conclusion that kinetic energy of bullets is transformed to thermal energy by plastic deformation and fracturing of bullets because of the high-strain rates during impact. Fragments cool rapidly but can ignite organic matter, particularly fine material, if very dry and close to the impact site.

Risks to human health from ammunition-derived lead in Europe

“…As well as possibly causing fracture into larger particles, the kinetic energy of a bullet is partly converted, upon striking the target animal’s flesh, into a permanent change in shape of the projectile and into heat. The heat may cause some of the lead to melt or vaporize (Finney et al 2016). On cooling, very small nanoparticles of solid lead may form from the melt.…”

Determining Ricocheting Projectiles’ Temperature Using Numerical and Experimental Approaches

“…Numerous papers on ignition and fire have been published [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ], but the available sources show a shortage of references on fire ignition from ricocheting projectiles [ 16 ].…”

“…Research on the ability of various flammable substrates to ignite from ricocheting projectiles was carried out by the United States Department of Agriculture/Forest Service [ 16 ]. For the tests, intermediate ammunition: 7.62 × 39 mm, 5.56 × 45 mm and rifle ammunition: 7.62 × 51 mm, 7.62 × 54R was used.…”

Smoldering spot ignition of natural fuels by a hot metal particle

“…There are a limited but growing number of studies published on the spot ignition of natural fuels by hot metal particles by the present authors and others. Most have studied the problem through experiments [17][18][19][20][21][22][23][24][25], but there has also been some of modeling of the phenomena, with several simplified models ranging in success and complexity. "Hot spot" models originally used to model sympathetic detonation of explosives [26] have been adapted to the ignition of natural fuels by hot metal particles [19,27] with limited success.…”