I would suggest a Nub removal from the magazine if the mag has them. To check you just push down the follower and look at the steel walls under the feed lips inside the magazine. Should be triangular polymer nubs on both sides.
I had misfeeds originally with mine, read a thread a few months back on failures to feed, shaved those nubs off with a sharp blade, feeding flawlessly ever since. /runonsentence
Found a pic from a different thread. http://i51.tinypic.com/2a649he.jpg