You're correct that it takes AR parts, but that alone doesnt make it restricted. What makes it restricted is the fact that it was designed based off of an AR 15/AR 10 making it a variant thereof, and therefore restricted. Even if you couldnt attach it to any other AR 10/15 it would still be restricted due to that fact. BCL got around this by designing their 102 after the earlier prototype to the ar 10. And the maccabee and atrs designs arent based on any AR design, they are unique but take many common components.