If NC has a permit or registry system, like a lot of the eastern states seem to have, then yes, it's possible.

Here in Colorado, until 2003, I as an FFL had to send in a record of each and every firearm bought from me to the local city PD pawn detail, and the city kept those records until the state passed local pre-emption and forced them to expunge their registry and destroy those files (if they actually did?)

Many places still have a permit system in place for handguns, so they'd be traceable that way, though that generally doesn't apply to long guns in most jurisdictions.

Unless one of those permit or registration systems exist, the cop can't trace the gun through ATF without having a make, model and serial number. Though it's possible he either leaned on or was buddies with the gunstore owner, to get that information.