I have seen some places list 20 parts and other places list 15. Which is it and what are they.
There are 20 "Countable" parts on the BATFE list, however a AK only contains (at most, stamped w/ MD) 16 of them.
(4) Muzzle attachments
(6) Bolt carrier
(7) Gas piston
(12) Pistol grip
(13) Forearm handguards
(14) Magazine body
A clarification for newcomers: Only the front trunion, correct?
cool! thanks fellas
Yes, you are correct. The trunnion into which the barrel is fastened is a countable part. The rear block, or rear trunnion, that sits at the back of the receiver is not a countable part.
There is only one trunnion, the part that mounts the barrel to the receiver.
Referring to the stock tang as a trunnion, while technically incorrect, has become accepted terminology amongst home builders, but it is not "countable".