I just checked the ATF site:
(B17) What recordkeeping procedures should be followed when two private individuals want to engage in a firearms transaction? [Back]
When a transaction takes place between private (unlicensed) persons who reside in the same State, the Gun Control Act (GCA) does not require any record keeping. As noted in FAQs B1 and B2, which are posted on this Web site in the "Firearms" section, a private person may sell a firearm to another private individual in his or her State of residence and, similarly, a private individual may buy a firearm from another private person who resides in the same State. It is not necessary for a Federal firearms licensee (FFL) to assist in the sale or transfer when the buyer and seller are "same-State" residents. Of course, the transferor/seller may not knowingly transfer a firearm to someone who falls within any of the categories of prohibited persons contained in the GCA. See 18 U.S. C. §§ 922(g) and (n). However, as stated above, there are no GCA-required records to be completed by either party to the transfer.
For information about any State or local regulations that may govern this type of transaction, it is advisable to contact State Police units or the office of your State Attorney General.
Please note that if a private person wants to obtain a gun from a private person who resides in another State, the gun will have to be shipped to an FFL in the buyer's State. The FFL will be responsible for record keeping. See FAQ B3 (Firearms).