Cribbed this from David Hardy's blog:
http://armsandthelaw.com/archives/2009/07/atf_issues_guid.php
Link to PDF: http://www.atf.gov/firearms/070709openletter.pdf
Commenters on the blog have noticed a new checkbox on the 4473 to indicate "receiver". Any of you FFLs have more info? On the one hand, you have to be 21 to buy a receiver. On the other hand, this would seem to indicate that it really doesn't matter if your AR receiver was first assembled as a pistol/rifle/whatever.
http://armsandthelaw.com/archives/2009/07/atf_issues_guid.php
Posted by David Hardy · 13 July 2009 08:41 PM
Pdf here. Gist appears to be that a bare receiver is a firearm, but not a rifle, shotgun or handgun since it can be made into any of them (which I think may be true in some cases, but not in most). Ergo, (1) a bare receiver must be logged in by an FFL and cannot be sold to a nonresident, (2) since it is not a rifle or shotgun it cannot be sold to a person under 21, but (3) since it is not a handgun, either, multiple sales need not be reported.
Link to PDF: http://www.atf.gov/firearms/070709openletter.pdf
Commenters on the blog have noticed a new checkbox on the 4473 to indicate "receiver". Any of you FFLs have more info? On the one hand, you have to be 21 to buy a receiver. On the other hand, this would seem to indicate that it really doesn't matter if your AR receiver was first assembled as a pistol/rifle/whatever.