I have a G-17 with well over 10K Lee 124 gr. bullets through it. Very minimal leading, almost nonexistent. Only lube I use is LLA(White Label). When I got the gun, I also purchased a aftermarket Lone Wolf barrel. I bought into the hype. I had significant leading issues. Switched back to the factory barrel and the problem was solved. I also own a G-30 in .45 ACP that has been fed nothing but cast from day one. Zero leading, excellent performance.
The only Glocks that have cast bullet issues are owned by inexperienced reloaders, or are chambered in .40 S&W, or both.