so if i have a rifle in factory setup, and put a stock on it with a pistol grip, it is ok to have as long as I only use a 5 round mag. As soon as I would insert a mag larger than 5 i have to fall within 922, even in a factory setup.
So basically as I see it, I can put a new stock with pistol grip onto the saiga 7.62X39, as long as I change the the forearm grip (which I plan on doing at the same time), and using US made magazines (unfortunately promag for now), I am fine.