[New York police] officers - five are still on the force, and three are retired - and four other men were accused of transporting M-16 rifles and handguns, as well as what they believed to be stolen merchandise across state lines, according to a complaint filed in the case in Federal District Court in Manhattan. The gun-trafficking accusations strike at the heart of one of the Police Department's most hard-fought and robust initiatives, and one that has been a central theme of the administration of Mayor Michael R. Bloomberg: getting guns off the city's streets. Mr. Bloomberg is the head of Mayors Against Illegal Guns, a coalition of 600 municipal chief executives from around the nation. [NYPD], the largest municipal police force in the nation, [is] already besieged by corruption accusations. In recent weeks, testimony at the trial of a narcotics detective has featured accusations that he and his colleagues in Brooklyn and Queens planted drugs or lied under oath to meet arrest quotas and earn overtime, leading to the arrests of eight officers, the dismissal of hundreds of drug cases because of their destroyed credibility and the payout of more than $1 million in taxpayer money to settle false arrest lawsuits.