Can you post pics? That would help us help you. In my experience, metal mags worked fine with the SKS D, but the Bulgarian waffle mags I had, did not...
Cheers
Jay
Do you have a paddle or slide catch mag release? I bet you have a slide, right? If so, that's your problem. The slide catch was a poor design to hold AK mags, I've heard of lots of problems.
isn't that an SKS-M?