soft sided pistol holsters,including dropleg platforms, have a tendency to eject the mags,most times without the user nowing about it. i may have found a way to prevent this. all you need is an old bicycle tire tube cut in the appropriate size and fit it over the magwell. see illustrations below.
it fits really tight and even when the mag is released it takes pressure to fully eject the mag by hand, so accidental loss should not happen. i will be testing this on the weekend to see if it works.