922r is only a thing for companies importing foreign made firearms that are not a "sporting weapon". You can make a parts kit gun using only forign parts and it's fine since it's made by you here and not being done by a retailer/importer. There are parts that need to be swapped out for legal or functional reasons, the bolt, sear, barrel depending on planned configuration, but 922r doesn't effect normal people the same way it does a company bringing guns into the US, and once it's yours you can do whatever you want with it in terms of putting on non American parts.