First thing I would do is color the extractor, work the slide and see if the color is rubbed off anywhere. About the only place that should make contact is the inside edge of the extractor as it goes to battery. I had this happen on one firearm I was tuning up. The extractor was "fat" just in front of the hook. It made contact with the extractor cutout in the breech and pushed the bolt back as the bolt came to battery.How would I go about loosening it?