An update for anyone who follows such things.
After contacting CMMG again they suggested I try using Winchester White Box. Strangely enough, it seemed to run a lot better. There were still a couple of misfeeds, but there was a noticeable increase in reliability.
Does anyone have any suggestions why WWB would make a difference? Of all the other factory ammos (AE,S&B, Independence,UMC) I tried I just have a hard time swallowing the pill that the preferred ammo for this firearm is WWB.
I'm still tempted to buy another buffer spring and take off a coil or two or try a different buffer.
WWB there over all length tend to be longer than others..........can you bend the feed lips on the mags in any????