I'd say the ejector is out of wack and not sending the brass out the side properly. I'm not a smith though so this is just my guess. Have a glock armorer look at it or call Glock and they'll look at it. Show them this picture and I'm sure they'll take it and fix it up. I know my friend had an old Gen 2 G17 with a bulge in the barrel that he wanted to get looked at in case it was going to be a problem. He didn't know the history of the internals so he called Glock. After he got the gun back it had everything replaced inside. Basically got a new gun. I figured it's so cheap and easy to swap out all the parts and springs and test fire rather than try to diagnose any possible issue. On a 1911 maybe not, but a Glock is a very simple design by comparison.