Yep it happens . The other day I had 2 failers to fire and 3 feed jams in one 10 round mag . It was the first mag of the day . I did nothing to the gun just loaded the next mag and all was good .Put another 200 rounds through it that day with out one problem . Boy I'll tell you what . Those first ten shots had me thinking there was something very wrong with my gun . I never realy found out what the problem was . I think it was the mag . I've been having problems with the two older 20 round PMAGS I have . I did not use either one again that day .
As of this date 8-18-14 at 6:42am I became a proud grandfather I guess I'm officially old