The 16 countable parts of an AK rifle. No more than 10 of these parts may be imported.
(1) Receiver*
(2) Barrel **
(3) Trunnion
(4) Muzzle attachments(flash hiders, brakes, barrel extensions, barrel nuts)*
(5) Bolt
(6) Bolt carrier
(7) Gas piston*
(8) Trigger*
(9) Hammer*
(10) Disconnecter*
(11) Butt stock*
(12) Pistol grip*
(13) Forearm hand guards*
(14) Magazine body **
(15) Follower **
(16) Floor plate **
The parts with the * are the most commonly available U.S. manufactured parts.
On a typical stamped receiver rifle you need to replace 5 parts with no muzzle attachment and 6 parts with a muzzle attachment.
On a typical milled receiver rifle you need to replace 4 parts with no muzzle attachment and 5 parts with a muzzle attachment, because there isn't a barrel trunnion, it is part of the receiver.
When building an AK pistol, these regulations do not apply. You can not have a stock or forward pistol grip on a pistol.