I started having the type of FTE where a round chambers, but the empty case gets caught in the ejection port(not a stovepipe). I traced the occurrence to some new Wilson 7 round mags. It would happen once per mag in the first two rounds. I have since fired another 100 rounds with other mags, and it has yet to happen. The recoil spring is standard weight with about 450 rounds on it and the firing pin spring is extra power replaced at the same time. Again, it only seems to happen with those particular mags. Any other suggestions?