Transporting a firearm that is unlicensed and unregistered in New Jersey is a criminal offense that will expose the defendant to a mandatory period of incarceration. This is the case even if the firearm/gun is legally registered in another state. HOWEVER, there are some exceptions to this which can be found at the State Police Transporting Firearms website page
This offense is most commonly prosecuted under the authority of NJSA 2C:39-5, Unlawful possession of a Weapon/Firearm. For more information on this offense, please see my unlawful possession of a firearm/weapon article which will describe the offense, penalties, and law more thoroughly. This offense is almost strict liability in nature and will require the assistance of an experienced NJ criminal lawyer. If you have been charged with unlawful possession of a weapon while traveling through New Jersey, you may contact my office 24 hrs to discuss your charge and possible defenses.