Some question what is part of the 922r rules, I made a list that clarifies any confusion. I made this after a couple years of on and off research.
Tapco also made a kind-of essay on why some things are and are not covered and why some things contradict things are are not a part of the rifle. http://www.tapco.com/section922r/
"There are arguments like “the SKS does not have a pistol grip so that is not a compliance part for the SKS”. If your SKS has no pistol grip and you choose not to add one, then this is correct. BUT, if you buy an aftermarket stock that contains a pistol grip, you have just added a part that is in the parts list and it will count against you if it is not U.S. made. It does not matter if the platform does not have a covered part normally, it matters what you have on your rifle or shotgun."
Multi-nation SKS Compliant 922(r) list: (Normally, only 14 parts to a typical SKS; *possibly 15 for the Yugo version)
- Bolt carrier
- Gas piston
- Trigger housing
- Magazine body
Optional parts covered by 922r: (Except for the possibility of the Yugo version, these parts are also considered a parts of the SKS, but only if added. Which makes it a total of 17 possible parts on an SKS)
- Floor Plate (Only with replacement magazine with floor plate)
- Muzzle Device (Only if attached permanently or non-permanently to the SKS)*
- Pistol Grip (Only for stocks with a pistol grip)
Parts not a part of the SKS:
- Barrel Extensions
- Mounting Block (Trunion)
- Operating Rod