Somebody please tell me how a FFL is going to be able to run a background check through NICS and complete the 4473 on merchandise that has never gone through his bound book.
Guess you haven't been to Kalifornia since about, oh, 1999?
All firearm sales, including personal transactions, require an FFL with background check out there.
Wanna sell a buddy your gun? You both head to an FFL dealer, the seller surrenders the gun to the FFL, who then runs the check, does the 4473, and initiates the waiting period.
When the NICS check comes back ok and the waiting period has completed, the buyer is free to retrieve his new firearm from the FFL holder.
IIRC, the FFL charges a nominal fee for the service.
(Of course, that's what the residents who choose to abide by that law do. I can't speak for those who still buy/sell the old-fashioned way...)