but often disintegrate upon striking glass. Hard targets may be damaged by frangible bullets. Extent of damage increases with velocity of bullet impact. Energy transfer at the point of impact may break brittle targets, and may temporarily soften and permanently deform malleable materials. Target crystalline structure may be changed to increase target damage by subsequent bullets. Steel targets designed to withstand rifle ammunition may be damaged by bullet velocities over per second; and lower velocity bullets may damage steel targets intended for pistol or rimfire ammunition. Frangible bullets striking animal targets create wounds similar to conventional bullets. Some penetrate soft tissue similar to full metal jacket bullets. Some may disintegrate upon striking bone. Hunting bullets include a frangible core designed to disintegrate when a protective jacket is opened by softer tissue or fluid. Frangible bullets disintegrating in flesh cause very serious wounds with persistent effects. Frangible bullets may represent an unconventional threat to personal armor intended to resist traditional lead bullets. At the request of the National Institute of Justice, staff of the Office of Law Enforcement Standards, located at the National Institute of Standards and Technology, has conducted a limited series of tests evaluating the performance of frangible ammunition against body armor. This preliminary study was designed to attempt to establish the validity of claims that these types of rounds pose a potential safety threat to personal body armor. The true scope and relevance of this threat was not known as of November 2002. Uses Frangible bullets offer improved safety for specialized combat simulation training, which involves one or more shooters engaging multiple steel targets from various directions while moving through a 360 degree range, due to the decreased risk of ricochet, overpenetration, as well as decreasing lead exposure. Frangible bullets are also used in reduced ricochet, limited penetration (RRLP) loads intended to reduce risk to friendly forces and innocent persons during close quarters military or police actions in urban areas, aboard ships or aircraft, or in hazardous material environments like oil platforms and chemical or nuclear plants. History Injuries from lead bullet fragments ricocheting off metal targets at 20th-century amusement park shooting galleries encouraged development of frangible bullets in specialized .22 Short gallery loads including Peters Krumble Ball, Remington Spatter-Less, Western Kant-Splash, and Winchester Spatterpruf. The United States used frangible lead/Bakelite M22 bullets in aircraft .30 caliber machine guns for target practice at armored RP-63 manned target aircraft.