Quoted:
The serial numbered part is the Lower receiver.

You can have an Upper built for you but you cannot do a form 1 and then have someone else buil the rifle.
The upper is not the weapon, as long as they are only doing the upper it is not a problem.

This is on a SBR where the barreled reciever is the serial numbered part for the Form 1 (PS90).

Quoted:
Once you have the approved Form 1 in hand (and your name engraved on the reciever) it doesnt matter who cuts or swaps the barrel. And the reciever is the serial numbered part, barrel or lack there of does not matter.

Kharn

If you already have a PS90 and have an approved Form 1 send us the barrel ONLY, along with a copy of the approved Form 1, and we will cut and crown the barrel, thread it M12x1 LEFT HAND and ship it back to you with a thread adapter for you to install in your receiver.  The cost for this conversion is currently $156.00 and does NOT include engraving the receiver.  Under Current BATFE regulations if you do the Form 1 conversion your name, city and state must be engraved on the receiver in plain sight in letters at least 1/16” high and at least .003 deep.

Quoted:
With my approved Form 1 - with myself as the "maker", can an SOT 03 do the actual rebarreling?

This is on a SBR where the barreled reciever is the serial numbered part for the Form 1 (PS90).

Quoted:
Once you have the approved Form 1 in hand (and your name engraved on the reciever) it doesnt matter who cuts or swaps the barrel. And the reciever is the serial numbered part, barrel or lack there of does not matter.

Kharn