I run WWB in FA all the time with no issues, but it wont run rem green box. when dealing with clones, some guns prefer different ammo choices so some T/E might help.
My vote would be the limpwristing (not literally), but it sounds like you are losing some of the energy required to cycle the gun, as exhibited from the varied ejection pattern. I'd try a sling and the push out method if able or be really conscious abt your shooting style. A stock would prob fix any issues (with a sear or SBR stamp, of course).
You might be able to place the gun on your hip or something solid and try a few rounds in rapid fire to see if the ejection issue goes away. Also, definately keep track of the mags and see if one is specifically causing the issue (mag sitting to high and slowing down the carrier speed and therefore slowing down the ejection process).
This is prob not your issue but: Take the bolt out. Can you move the extractor at all with your fingers? place an empty case in the bolthead. Can easily knock the round out of the bolt head with some side pressure? there used to be a video called the "zip tie test", when someone pushes on the casing from the side with a ziptie. If the ziptie can dislodge the empty case, your issue is an oversized bolt or an extractor issue.