Sorry to hear about the mag issues. As someone else mentioned, there really aren't a lot of quality aftermarket mags for Mini-14/30 rifles. For the longest time the only success I had was with Pro Mag polymer magazines.
Before Tapco released their Mini-14 mags, they sent me 4 to test.(I tested products for Tapco, Benchmade, SOG, etc..) I sent them 4 magazines back with an email saying they were horrible and not to move forward with releasing them into the market. They did anyways, and they paid dearly for it. However, they have worked out the kinks and the new Gen2 Tapco mags are fine. My advice would be to try one of those two brands and go from there. Best of luck to you.
GB