FWIW Had a similar problem with my Mini-30s not feeding properly. With Pro-mag mags it was too much spring in the mags....cut a coil and a bit and they fed fine. With the factory ones it came with, it was not enough spring pressure to feed properly.....stretched the spring and they worked fine. Just have to tinker with them sometimes. Also check the feed lips for contact on the cartridges....might have to adjust them a little.