That's over-gassed... Or under-recoiled, but not in your case here, with the changes you've made already to the recoil system. I might have missed it, but did you change out that recoil spring (buffer spring).
If you HAVE put the Armalite EA1095 spring in there, then this is the reason that it's a description of "over gassed" - that BCG is FLYING. That gas PRESSURE (where's my "gas temperature" guy?...) is too much, and it's forcing that BCG to unlock before that now-empty brass case cooled enough to retract. What happens to the brass is violent, and it expands, and sticks to the chamber walls. Gas pressure too high, the unlocking process starts too soon, and the case walls are still stuck to the chamber - the EXTRACTOR loses grip of the round/case. The bolt releases the case, and it's not extracted fully yet, and it's just floating around in your chamber - the EJECTOR never got to really do it's job and fling that case out of the rifle, because the EXTRACTOR lost control of that hot case before it was back far enough to clear the ejection port.
HOT LOADS can cause this, too, exactly like this - and I didn't see you mention any specific ammo that you were using. Please list the ammo specifics that you were shooting when this happened.
Caps were used to emphasize the parts, and their function, not to "yell at anybody..."
That make sense? Under-recoiled guns will do the exact same thing - smaller gas ports, and lower gas pressures will do that, when you have a too-light recoil system (buffer) or an under-sprung recoil system (weakass spring that's not up to the task here) - and it can't keep that BCG in place long enough for that brass to cool, and be extracted "when it's time to be extracted." Your recoil system needs to "have enough ASS to control the MASS" of that heavy BCG, and the PRESSURE that the gas system makes, through this .308 Win round...
Hope the information comes across as I intended it to - if not, ask questions about it.