One of America’s most popular guns is a “ticking time bomb” that allegedly fires spontaneously and has injured dozens of cops.The SIG Sauer P320 semi-automatic handgun is used by some 1,000 law enforcement agencies from the local to the federal level, as well as being a popular civilian purchase.But its manufacturer is facing a slew of lawsuits alleging that it can fire even when holstered, even when the trigger isn’t pulled, and even when it is just sitting at rest, lawyers allege.According to the suits against SIG Sauer, some 150 people claim to have suffered injuries, or frightening near misses,...