The last iteration of C-Products 7.62x49 Mags were quite good. I have 10 of the 20 round mags and a few 10s & 30s.
All of them have fun flawlessly, Both Steel case and hand loaded brass cases.
If the DuraMags are just the same C-Product design rebranded, then that’s probably the best 7.62x39 AR mag you can buy currently.
I had poor experiences with ASC mags, and gave them away.