Pistol upper legal to own?

[SDW]

There's no such thing as a pistol upper. It's the lower that you have that's the firearm.

First the I'm-not-a-lawyer disclaimer. But I agree with you and others. No such thing as a "pistol upper". In fact, if an LEO were to find such a thing in search, it could instead be assumed to be the component to construct a short-barreled rifle. Could get you into hot water, depending on the jurisdiction. "Constructive Possession"? Possibly.

I wouldn't build a short-barreled upper. Don't own any pistol lowers.