But... I believe it has to start out as a duckbill mag so the material is there for it to latch.
LC, you are 100% correct. They must be standard duckbill, SKS, 7.62x39, polymer mags to start out. We modify them to run with our adapter. SO, no more duckbills. And they run better than with the duckbills on them. And store better too. No, those mags from the link are AK mags and won't fit the receiver well.