I was out plinking yesterday (and bagging trash) when my M&P 15 .22 started jamming. It turned out to be the magazine. The magazine body started coming apart and allowing the follower to push the round up through the top. The rim of the case has caused two small grooves in the feed lips where the round remains trapped and won't feed. This mag has less than 1000 rnds through it. I'm awaiting a response from S&W. In the mean time has anyone ever had this problem before?