he's asking about it taking AK mags, Saiga mags have an integral feed ramp to them. Saiga-12s don't take standard AK mags and require no feed ramp to be installed.
I had one (7.62x39), and all it took was a little feed ramp modification with a Dremel. The Saiga mags pushed the shells up into the chamber, where the AK mags didn't, the rounds came out straighter. The chamber just needed more ramp at the bottom to kick the rounds up.It always failed to feed the last round from the AK mag, but since there isn't a empty mag hold open feature, that was kind of a good thing. Besides that, if I recall correctly, the mags fit fine.
You can tell the difference in the mags by looking at the front of them. The Saiga mags have a higher lip in the front that helps kick the round up and into the chamber. I thought about modifying the mags (welding on a little addition to the front), but it was easier to modify the feed ramp of the rifle.
Try to cycle the rifle by hand with an AK mag, and you will see what I mean. The rounds run into the bottom of the chamber. It just takes a little work to make it feed right.
Just go to www.carolinashooterssupply.com order the trunnion ramp comes with drill bit ,tap,screw and ramp. It only fits one way and takes about 15 minutes.
Then order you a mag of the size you want from him. I have done 6 of them.