On the saiga 223, there are a couple different methods that people do.
(1) Bulgy/Polish 5.56 conversion - requires modification of the underside of the locking lugs and some catch work (done this)
(2) Weiger 223 (metal German mags) - opening up of magwell, and some other tweaks (never done this method)
(3) Galil / M16 adaptor - requires ALOT of work, but it does work. You can get a Galil 5.56 AR mag adaptor for around $70, then do a bunch of mods. Cool way to get UNMODIFIED ar15 mags to work in a AK. (look @ www.saiga12.com there is a thread in the 223 saiga section)
I prefer to modifiy the gun to fit the mags. I currently own 2 5.56 AKs.
One is a Milled SAM 5, and the other is my Custom Saiga KRINK.
Both take unmodified Bulgarian/Polish 5.56 magazines.
I am hoping to get another saiga 223 for a new project . THANK YOU whoever posted that link to EE, I can't beleive I missed that saiga.. I emailed a offer.
Wish me luck