Low capacity Saigas are imported as-is
THEY HAVE NO U.S. PARTS, as long as they have the "Sporter" stocks and low-cap mags they are legal under 922r. IF you modify the weapon to accept normal-cap mags then you MUST replace 7 parts to remain legal. The Stock, pistol grip, handguard, hammer, trigger, sear (get the Red-Star trigger group, it's more $ but well worth it, near match trigger) and gas piston need to be replaced to make it legal.
One Source Tactical is the only place I know where you can get all of it.
http://www.onesourcetactical.com/index.asp?PageAction=VIEWCATS&Category=284It is pricey to do, but well worth it.
P.S. if you rely on US mags to make content you cannot use OR OWN imported mags. If you have the imported mags in your house you can be charged! You don't need to put one in the weapon, likely to happen? Maybe not, but I won't risk the fines and jail time myself.