I assumed Mr.Tinker was referring to the nice folks at the bureau.
Thank you for clarifying
at least you dont have to do s.b.r paper work w/stamp for an arty with a board
wich is not to be confused with s.v.r... unless you wanna a good chuckle

Your friends over at BATFE label this "intent to construct" and it can potentially get you into serious trouble. You cannot own a AR and a less than 16" upper in the same dwelling or readily accessible. Or full auto internals, regarless of the fact that your lower receiver is a semi-auto.
You can debate this all day long, (gee, if I own a shotgun and a hacksaw, is that intent to construct an SBS??), but if actual parts that fairly easely go together are present, a determined procecutior will ruin your day.