OK, let's get started: 922(r) covers the act of assembling a non-importable rifle from imported parts.
First is the "assembly" part: If you haven't messed with the rifle since it was purchased, you should be fine. In fact you're fine even when you purchase a non-compliant rifle from someone else. However, as you might imagine some folks are nervous about owning such a rifle. In the past, ATF has said that having a sales receipt or bill-of-sale that lists the specific configuration would be good enough proof (as always, YMMV).
Second, is the "non-importable" part: ATF has determined that SKS rifles with certain "non-sporting" features (such as telescoping or folding stocks, bayonets, grenade launcher / threaded muzzle, detachable magazines, etc.) are not importable commercially. (Note that this list of features is not quite identical to the features in the typical "assault weapons ban".) Thus adding those features to an already imported SKS rifle is prohibited. But what if you really want one of those features on your rifle? That's where the next part comes in.
Finally, is the "from imported parts" piece of the puzzle: ATF realized that many rifles made by US manufacturers contain some imported parts (screws, springs, etc). So they made up a list of 20 parts that are "counted". If more than 10 of those parts in a particular rifle are imported, the rifle is said to be made from imported parts. However, most rifles don't even come close to having all 20 parts from ATF's list. For example, the Russian SKS only has 14 of the parts from that list -- replace 4 counted parts with US-made parts and your entire SKS is no longer made from "imported parts". Yugo SKS have 15 counted parts -- you will need to swap out five. Note: The number of US-made parts doesn't matter, it's the number of countable imported parts that remain that's important. So just adding US-made parts, doesn't help you.
How C&R plays in #1: C&R rifles are allowed to have bayonets and grenade launchers (in the case of Yugos), but only when in their original military configuration. For example: If you install a synthetic hunting-style (aka: Monti Carlo) stock on your Yugo SKS, your rifle losses its C&R status and becomes subject to 922(r). You now have two "non-sporting" features: The Grenade launcher / muzzle threads and the bayonet. You have two choices to become compliant: 1) You can remove the GL & bayonet and solder / weld on a muzzle brake or "thread protector", or 2) swap out additional parts (FCG, magazine, gas piston, and GL are among the most common choices), until your rifle has 10-or-less imported parts from the list.
How C&R plays in #2: C&R rifles are allowed to have bayonets and grenade launchers (in the case of Yugos), but only when in their original military configuration. For example: If you install a telescoping stock (like the one in the advert on the top of the page) on your Yugo SKS, your rifle losses its C&R status and becomes subject to 922(r). You now have four "non-sporting" features: The telescoping stock, pistol grip, grenade launcher / muzzle threads and the bayonet. You only really have one choices to become compliant: Swap out additional parts (FCG, magazine, gas piston, and GL are among the most common choices), until your rifle has 10-or-less imported parts from the list.
And as always, YMMV . . . If you have additional questions, post them here.
Larry
PS: If you would like more information, click on the link in my signature.
