Quote History Quoted: If your rifle started out as a pistol AR, you could build it into a rifle and subsequently convert it back into a pistol. If your rifle started out as a rifle it remains a rifle.
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See, this is one of the many things about NFA that confuses people. If I take the stock of my AR, it becomes a 16" bbl ungainly pistol, b/c it started life as a pistol. If OP takes his stock off, it's still a rifle, b/c it started life as a rifle. Side by side, w/ the stocks off, they look identical. It's purely a legal distinction.
I'd love to see a set of pics, photoshopped if necessary, of an AR receiver, progressing through all the different stages of the NFA, from 80%, to pistol, to firearm, to PG shotgun, to sub-18" bbl PG shotgun, to shotgun, to rifle, to AOW, to SBS, to SBR, to machinegun (w/ RDIAS). Nearly all the pictures would be identical. I think similar things can be done w/ the T/C Contender & Encore, albeit not the machinegun bit.