"Frangible" bullets are designed to break into small bits when they strike a hard surface. This ammunition might appear counter-intuitive, but it is used by law enforcement personnel in areas where ricochets could harm innocent bystanders. Now the question has arisen as to how frangible bullets might behave should they strike the soft body armor worn by police and first responders. NIST researchers are using a Kolsky bar apparatus to find out. (www.sensorsmag.com/0706/RDBullet)