The Milwaukee police union is suing the city over service weapons that officers say aren’t safe because they have inadvertently fired without anyone pulling the trigger. It's the latest legal action involving the P320 model firearm manufactured by SIG Sauer. A case was filed in Philadelphia in June by a U.S. Army veteran who suffered a serious leg injury when his holstered gun discharged. The Milwaukee Police Association says the department-issued handguns have inadvertently misfired three times in the last two years resulting in injuries to two officers. The union is asking a judge to force the city to pay damages for the injuries and replace each P320 with another firearm.