A friend has asked me to help him diagnosing a problem. He has a AT-84S, the Swiss clone of the CZ-75. According to him. the gun will hand-cycle an entire magazine - feed, eject, extract. When he fires it live, after the first shot, the empty case is partially extracted, and the next round tries to feed - a classic double feed. The extractor hook and ejector are not broken or chipped, and the extractor feels like it has enough tension when pushing a live round from underneath. Any help ?