If you convert a rifle to an SBR, you fill out your paperwork, pay your tax and engrave the mfg (you) and location on the receiver.

If you buy a factory SBR, no extra engraving is required as the mfg info is already there.

My question is, does the factory have to designate the receiver as an SBR before it leaves the factory?  Is there anyway to purchase a stripped receiver (which can be listed on the 4473 as a rifle or pistol) and get it registered and papered before taking possession?

Quoted: If you convert a rifle to an SBR, you fill out your paperwork, pay your tax and engrave the mfg (you) and location on the receiver. If you buy a factory SBR, no extra engraving is required as the mfg info is already there. My question is, does the factory have to designate the receiver as an SBR before it leaves the factory?  NO, you must file the registration (form 4) when you purchase it. Example of a factory made SBR is a DS Arms OSW. Is there anyway to purchase a stripped receiver (which can be listed on the 4473 as a rifle or pistol) and get it registered and papered before taking possession? If it is simply a stripped receiver from which you wish to make an SBR you do not need  registration before ordering and taking possession of it  because it is not an SBR until you put a short barrel on it. Order the receiver as a normal firearm, get it engraved with your information and file the form 1. When you receive the form back approved with tax stamp affixed then you can put your short barrel on. If you want to buy a pre-registered SBR stripped receiver, you would have to find a dealer that will sell it like that (unlikely) and put a deposit down to hold it while your form 4 is processsed. You still have to have either incorporation or CLEO signoff, so it makes more sense to either buy a complete SBR on a form 4, or make your own on a form 1. It will typically be far less expensive to make your own SBR on a form 1

Thanks _dr.  That is pretty much what I figured.