... if the dealer chooses to complete the transfer. It's up to their discretion, though I'm sure most will complete the sale after the 3 business days.You seem to not understand how the NICS check works. The only thing that the government officially cares about in regards to buying multiple firearms within a certain time frame is handguns. An ATF form 3310.4 must be submitted if an unlicensed individual buys two or more handguns from one dealer within five consecutive business days.
Your 4473 information won't be "called back in" to NICS. You were either approved, delayed, or denied. If you were approved, you could have left with the gun. If you were denied, you won't be leaving with that gun. You were delayed if the dealer believes that you will end up getting the guns. If the FFL doesn't hear an update from the ATF in regards to your delay within three days, the gun's yours.