My gun has polished feed ramp, breech face, disconnector rail, as well as relieved/radiused/polished extractor hook; the problem really seems to be the mag not being able to lift the ammo column fast enough for the slide to catch the top round. 7- and 6-round mags with new springs work perfectly, while 8-rounders and/or old springs result in nose-dives. I suppose it could be an extractor tension problem, but the "problem" has persisted through three extractors.