Some states permit untracked, unreported -private- sales of handguns, as in, no dealer involved (Alaska does), and some do not.
you are indeed correct about handgun buys through dealers; my post was less than clear on that. Tennessee allows for private sales w/no background check, but they will make it rough on you for knowingly selling to someone not legally able to buy/own a firearm. i have heard proposals to mandate even private sales of used pistols be checked, and inherited guns as well.