I agree with the others. Your buffer and spring should be fine. I run a standard carbine spring with a heavy buffer in mine, you need to run a heavy buffer with most 9mm systems (blowbacks at least). I wouldn't touch the buffer spring. It would seem that the ejector is your issue if you are having problems, especially if it has wear on it. The 9mm ARs can be a little janky, but once they are running, they are a blast...
