photoracer
Competition Shooter
Had the same problem. Tried EVERYTHING and spent hundreds throughout a year. Finally got CMMG to put me on the line with their R&D devision and they immediately had an answer for a common issue. Your ejector needs to be bent inward about 6° using a deadblow hammer.
I had 2 cheap BCGs snapped off the gas block even with 2 screws. So I bought a better Faxon BCG, which has a flat face gas block and that has worked fine.
Mine works fine with aluminum case Federal but I only use it when I can't get brass case.