I own a 597 and love it. That said it has some things you must pay attention to:
- Always use the metal magazines or quality aftermarket ones. The plastic 10 round factory ones are prone to jamming.
- Keep the extractor squeaky clean. An exacto blade under the hook will clean it up.
- When tightening the set screws that secure the rails, be sure to snug them, and then back them off a half turn. the rails need a little room to float or you'll get binding and jamming.
Try those and if it still won't shoot right give me a shout and I'll do what I can help you out.