Seen the stoppage referenced in the contest thread, that is. Suppressed DPMS 11.5" carbine with a tight chamber. Was blowing primers & one wound up not in, but wedged over the top of the key. We took the opposite approach & removed the receiver extension, pulling everything out the back. Was still under warranty, so we sent it back & they rebarreled it. In retrospect, a couple turns on a finish reamer probably would have straightened it out.
ETA: Corrected barrel length.