Pilate: Take the slide off the pistol and remove the barrel. Put a cartridge under the extractor and see if it remains there . Flip the slide a little and see if it still remains there. Rotate a quarter turn and repeat, then repeat again and again.If it works loose, disregard what the Gooroos say in their shop manuals, and bend the extractor shaft slightly to very sllightly increase the grip on your case. Some genius may have filed the hook and loosened it, so you may have to replace the extractor.
There is also a possibility that some of the case heads are bent slightly due to improper fitting of a tight barrel, resulting (after firing) in a case head that is bent. At certain rotations, the cases will be tight, and at others they will be too loose. The fix is to have the barrel properly fitted, or to stop using range pickups for reloading. Somebody left them there for a reason.
Heed George's advice about retaining a tight grip. The tendency is to loosen it as the string progresses, to escape the full impact of recoil.
