Seriously am I the only one who knows ATF has a web site...
www.atf.gov ...
From there I get (sorry the cut & past spaces it funny, but if you are too lazy to look it up on the ATF site I am too lazy to make it look "pretty" here):
(E8)
May a licensee who has firearms
in his or her private collection
sell any of these firearms without
making firearms record entries?
A licensee may sell a firearm from
his or her personal collection, subject
only to the restrictions on firearm
sales by unlicensed persons, provided
the firearm was entered in the
licensee’s bound book and then transferred
to the licensee’s private collection
at least 1 year prior to the sale.
When the personal firearm is sold, the
sale must be recorded in a "bound
book" for dispositions of personal
firearms, but no ATF Form 4473 is
required.