Pistol upper legal to own?

[dpete]

Why do companies sell pistol uppers and weapons if there is "no such thing"?

Pure marketing BS to the masses who don't know any better. As has been stated, a pistol upper does not exist. A short barrel upper certainly exists. Pistol and Rifle lowers certainly exist. Put that short barrel upper on a pistol lower and you have a pistol, sold as a pistol. Put that short barrel upper on a rifle lower and you have a SBR that you better have a tax stamp for before you do it.