Don't know what you are shooting but if it is a center feed sometimes the ears on the magazine top are a bit too high and they knock the brass out before ejection. Another fix is to buy a larger diameter ball bearing that fits under the extractor. One of the members here sells them. The larger bearing is better whether it completely cures the problem or not. One other thing can be the extractor. Sometimes the case does not snap under the ledge on the front of the extractor but rides up on it.
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