There are many answers. None are perfect. One, call the press and humiliate him for being risky and stupid. Two, call the ATF and report him for suspected firearms violations. Three, bypass the police and talk to the district attorney. Four, contact an attorney about sending a certified mail cease and desist letter. All these have draw backs. None of these are friendly. However, the key is that you cannot let him continue to shoot up your place. The risk to family is too great.