We used to be able to get the flush fit steel 5 round SKS mags here, I have one on a Chinese SKS. They are very good quality and function fine, never had a problem with FTF's. Unfortunately the supply has all dried up and they are in demand on the second hand parts market. We can get a almost flush fit synthetic one, not as nice but useable.
Here are some pics of the Chinese steel flush fit 5 round mags -
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