Prosecutors in four Pennsylvania counties have announced new technology for helping trace guns that they say will be a “game-changer.” A device called a National Integrated Ballistic Information Network machine analyzes and compares bullet casings. Officials say when it’s connected to a corresponding national database, it will allow detectives to match fired casings with the guns in the region they originated from significantly faster. Officials can also test-fire a suspect gun to possibly match it to weapons used in previous shootings. The machine was purchased with federal funds for use in Bucks, Chester, Delaware, and Montgomery Counties.