Went out today with a friend who was shooting his AR-15 with the CMMG .22LR conversion. It only cycled 2 good rounds then failed to reset the trigger. This was often followed by what sounded like a double shot. He had Winchester 40 grain 1300 FPS. Same with some Browning 40 grain 1435 FPS ammo. It worked fine last time he used it. Suddenly it's short stroking. But there's another issue, as seen in the photo that might be part of what sounds like a double shot. I also noticed a flash at the BCG on the "double shots." This happened quite a lot. Not sure if this (as seen in the photo) is also causing the double shot. Any ideas?