State laws vary.
Check yours.
The only state that I can say for certain would have some grey area there would be Utah. Any 'handgun' with an overall length,
"not including any revolving, detachable, or magazine breech," over 12 inches is difficult to categorize in Utah. Depending upon how you interpret the definitions, it is a 'Dangerous Weapon', or a 'Firearm', or maybe both. But, it is definitely
not a handgun.
...But Utah licenses concealed 'weapons', not just handguns, so it's almost a moot point.
(It used to be worse. They fixed the definitions of 'Dangerous Weapons' and the 'Firearm' catch-all a few years ago. Prior to that, a handgun that exceeded the state definition of overall length could have arguably been classified as an unlicensed Short Barreled Rifle.
)
Federally...
This is still a 'handgun':
The photo was staged as a joke, but it was still legally a 'handgun' under Federal (and my state's) law.