I'd bet your extractor spring is worn out, and changing out the recoil spring for a new one would probably help. Wollf makes them, only a few bucks. Midway has a Wollf extra power extractor spring, ejector spring and recoil spring (factory weight) kit, you have to use their search function to find it, put in s&w 39 extractor spring. That will probably cure the problem. I believe Wollf also makes magazine springs. The original mag followers work well, too. Hope this helps.