[AnthonyG]

Ive got a King Arms M4 that has problems with certain mags catching. It's not that the magwell needs tape or Velcro, I have that, and mags don't shake around at all. The issue seems to be that the mags don't insert far enough to catch at all. The one exception are my King Arms mags which I measured with my callipers, and they seem to have a marginally shorter distance between the top of the mag and the catch notch.

I foresee a few solutions, and I'd like some opinions. I could grind down the top of the mags to make them insert farther, or I could grind down the the bottom part of the gearbox that extends into the magwell.

Are there any other things I could try, or has anyone experienced similar problems?