Careful there. 922r also applies to "assault weapons built with imported parts". Ten or more imported parts will turn it into an illegal assault weapon instead of a "semiauto sporter". Bottom line is any more than ten imported parts in a gun and it's a 922r violation.
+1
This is taken from:
http://atf.treas.gov/regulations/27cfr178.html
Sec. 178.39 Assembly of semiautomatic rifles or shotguns.
(a) No person shall assemble a semiautomatic rifle or any shotgun
using more than 10 of the imported parts listed in paragraph (c) of this
section if the assembled firearm is prohibited from importation under
section 925(d)(3) as not being particularly suitable for or readily
adaptable to sporting purposes.
(b) The provisions of this section shall not apply to:
(1) The assembly of such rifle or shotgun for sale or distribution
by a licensed manufacturer to the United States or any department or
agency thereof or to any State or any department, agency, or political
subdivision thereof; or
(2) The assembly of such rifle or shotgun for the purposes of
testing or experimentation authorized by the Director under the
provisions of Sec. 178.151; or
(3) The repair of any rifle or shotgun which had been imported into
or assembled in the United States prior to November 30, 1990, or the
replacement of any part of such firearm.
(c) For purposes of this section, the term imported parts are:
(1) Frames, receivers, receiver castings, forgings or stampings
(2) Barrels
(3) Barrel extensions
(4) Mounting blocks (trunions)
(5) Muzzle attachments
(6) Bolts
(7) Bolt carriers
(8) Operating rods
(9) Gas pistons
(10) Trigger housings
(11) Triggers
(12) Hammers
(13) Sears
(14) Disconnectors
(15) Buttstocks
(16) Pistol grips
(17) Forearms, handguards
(18) Magazine bodies
(19) Followers
(20) Floorplates