Another thing it might be. It looks like his extractor is frozen in place. My brother had a DPMS that had the same problem. They didn't finish cutting the opening in the bolt and the extractor could not move. It would lock the gun up with the 1st round fired. (Good thing they test fired it before it left the factory...
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Take the extrator off the bolt. Make sure there is nothing causing it to bind. With it assembled it should be free to move. If you can't, it isn't working right and whoever produced the rifle needs to replace the bolt.