A different firearm purchased by the same transferee/buyer may not be added to the Form 4473 after the transferor/seller has signed and dated the form. A transferee/buyer who wishes to acquire a different firearm after the transferor/seller has signed and dated the form must complete a new ATF Form 4473 and undergo a new National Instant Criminal Background Check System (NICS) check.
A federal firearms licensee (FFL) may amend Section A of the Form 4473 if the transferee/buyer decides to buy a different firearm than was initially recorded in Section A, provided the transferor/seller has not signed and dated the form.
[27 CFR 478.102(c) and 478.21]