Jon Wells It is a popular handgun used by police departments in Massachusetts and across the country, but it appears to have a dangerous flaw: At times, it fires on its own, without the trigger being pulled.5 Investigates first shined a spotlight on the issue last fall and has now learned about new problems with the weapon. The weapon at issue is the Sig Sauer P320 handgun, which is carried by hundreds of police officers here in Massachusetts.It recently became the official sidearm of Canada s elite military unit, Joint Task Force 2, that is until one of the new guns fired on its own and shot a soldier in the leg.Network correspondent Murray Brewster broke the story for CBC News in Canada, where he has covered the military for more than a decade.“The incident was serious enough for the Canadian military to remove all of the brand new P320s from service and put them on the shelf until they could figure out exactly why it went off,” Brewster said. “Informally,