>>27679071922r literally only matters if you're an FFL or importer.
I challenge you to find one solitary case of someone being convicted and sentenced over 922r alone, it's not realistically possible for anyone to prove that you violated it, and the Feds know this.
How would it happen? Is some dude in a suit gonna approach you and address you like fucking Bane, demand you tell him where the piston/floorplate/hammer/whatever on your AKM was made, and demand you to admit you put it together yourself?