When complaint shall be made on oath to any magistrate authorized to issue warrants in criminal cases that any pistol or other weapon or device mentioned in this act is unlawfully possessed or carried by any person, such magistrate shall, if he be satisfied that there is reasonable cause to believe the matters in said complaint be true, issue his warrant directed to any peace officer, commanding him to search the person or place described in such complaint, and if such pistol, weapon or device be there found, to seize and hold the same as evidence of a violation of this act.