Take a look at the NC DOJ web site on firearm laws. (Link Removed) My (non-lawyer) reading is that you can purchase a pistol from a private person at 18 as long as you have a pistol purchase permit, and can carry it openly in your vehicle. (But again, I am not a lawyer, so this is my personal reading.)
To quote the DOJ (Section VI): "North Carolina law does not currently address specific age requirements for the purchase of weapons. Rather, it looks to the federal standards for such restrictions. Under federal law, 18 U.S.C. § 922(b)(1), federally licensed gun dealers are prohibited from selling handguns to persons under the age of twenty-one (21). Further, all other purchasers of shotguns and rifles are required to be at least eighteen (18) years of age. Therefore, while a pistol purchase permit can be issued to an individual eighteen (18) years of age or older, such persons aged eighteen (18), nineteen (19), and twenty (20) could not use the permit to purchase a handgun from a federally licensed firearms dealer". (emphasis added)
Concerning carry in a vehicle (Section IIID): "While a weapon carried openly in an automobile would not be concealed, there are other problems specific to this method of carrying a weapon. The principal drawback, of course, is in the event of an individual being stopped by a law enforcement official, the officer may not readily know that individual's purpose and intent for carrying a weapon. As such, it is imperative that an individual immediately notify an officer of the presence of any weapon in the automobile, for the officer's and the vehicle's occupants' safety. "
