I’d say just use it and hope for the best. I can’t see buying a bunch of parts. My (very unfavorable) experience with this gun is nothing to write much about here but if your gun is working OK now, maybe an extra recoil spring and that’s about all. I would test it thoroughly before using it (the gun, not the spring). I doubt seriously this gun is going to make it to 5000 rounds. And yes, four magazines should be enough. Good luck.