Recently bought an 8" CMMG upper for my Anderson Defense Mfg. lower. Had FTE issues with most ammo, but CMMG has provided excellent support. I tried new ejector and extractor springs with no success, but when I installed a new extractor assembly the gun now runs 100% with everything from defensive loads to very soft competition loads. CMMG has also sent me a new bolt (in the mail) in advance of my having tried the extractor swap out. This is all with a standard carbine buffer setup.