Big Daddy Yep cmmg was a four letter word around here couple maybe a few years back...been awhile and I cant place where the problemo was upper or lower...or the set? search for it in here....ill do the same...maybe you will have good luck with it....hope so Wash
pmag problemos and Robo said sumthin bout the cmmg grip screw causing ftf's ......Survival here has a cmmg...get ahold of him