Transactions made by licensed dealers are listed down the page at the web site, they're required to complete a 4473 for any transaction just as the recieving FFL would for a transfer between individuals in 2 different states. A face to face or shipped transaction between 2 unlicensed individual residents of the same state does not require FFL involvement unless it's a handgun being shipped.
Those rules listed in my previous post apply to non-licensed sellers/buyers. And as I mentioned before, check state and local laws, a good example of this is California which has more stringent regs than the ATF, even some cities like NYC have more stringent regs, so be sure to check those out so ya don't get into trouble.
If you have any questions, be advised to check with the ATF for help at one of their field offices.
Tim
http://www.atf.gov/field/index.htmhttp://www.atf.gov/firearms/faq/B. UNLICENSED PERSONS
(B1) To whom may an unlicensed person transfer firearms under the GCA? [Back]
A person may sell a firearm to an unlicensed resident of his State, if he does not know or have reasonable cause to believe the person is prohibited from receiving or possessing firearms under Federal law. A person may loan or rent a firearm to a resident of any State for temporary use for lawful sporting purposes, if he does not know or have reasonable cause to believe the person is prohibited from receiving or possessing firearms under Federal law. A person may sell or transfer a firearm to a licensee in any State. However, a firearm other than a curio or relic may not be transferred interstate to a licensed collector.
[18 U.S.C. 922(a)(3) and (5), 922(d), 27 CFR 478.29 and 478.30]