<P> The ability to compare ammunition is a direct result of the invention of rifling around the turn of the 16th century . By forcing the bullet to spin as it travels down the barrel of the weapon the bullet 's accuracy greatly increases . At the same time , the rifling leaves marks on the bullet that are indicative of that particular barrel . Prior to mass production of firearms , each barrel and bullet mold was hand made by gunsmiths making them unique . The first successful documented case of forensic firearm examination occurred in 1835 when a member of the Bow Street Runners in London matched a recovered bullet from a murder victim to a specific mold in a suspect 's home confirming that he made the bullet . Further evidence that the bullet maker was the perpetrator was found in his home and he was convicted . As manufacturing and automation replaced hand tools , the ability to compare bullets became impossible due to the standardization of molds within a specific company . However , experts in the field postulated that there were microscopic differences on each barrel left during the manufacturing process . These differences were a result of wear on the machines and since each new weapon caused a tiny amount of wear , each barrel would be slightly different from every other barrel produced by that company . Also , each bullet fired from a specific barrel would be printed with the same marks , allowing investigators to identify the weapon that fired a specific bullet . </P>
when was the first documented case of tool mark identification
1835