It is. It is pretty far removed from some "database of gun owners" though as there's no way to survey all those records in all those filing cabinets in all those gun shops in all those states, to try and figure out who owns guns.
If a gun is found at a crime scene the investigators can contact the manufacturer and give them the model and serial number. The manufacturer will look up that number and tell the investigators what distributor bought that gun. Then the investigators can contact that distributor and give them the make, model, and serial number. The distributor will look through his records and tell the investigators to what gun dealer he sold that gun. The investigators can then contact that dealer and give them date the gun was delivered to their shop and the model and serial number. The dealer will then look through his records from that year, find that 4473 form, and tell the investigators what person originally bought that gun, and their address at the time.
Then the investigators can try to locate that person at that address. If no luck there, they can track down folks in that state with that name and see if they can figure out where that person might have moved, and if they're still in the state. If they can't find that person, the trail goes cold.
If, by chance, they can locate the original purchaser, they can inquire if that person still owns that gun, and if not, if they know the name and address of the next purchaser. There's no (federal) law that the seller has to even know the person's name he's sold a gun to, so if he says, "nope, sorry," the trail goes cold. If the gun was stolen, the trail goes cold. If at any point in the whole chain of custody one person doesn't have the contact info of the next owner, the trail goes cold. If at any point an owner moved to another state, the trail almost certainly goes cold. Etc. etc.
Tracking guns down that way is a bit of an investigative act of desperation. Few crimes are ever solved through information found this way as few traces would ever lead to the last person to have been in possession of that gun.