Finally got out for a dove hunt that went well, shooting 13 birds in less than 2hours. But my M2 12ga would occasionally bot fire the 3rd shell. It would fire, cycle, fire cycle, and click - nothing. I think the bolt wasnt being fully seated forward. I shot a variety of shells. All regular 2&3/4 lead factory bird loads: Winchester hi speed 7.5, 1ounce 1350fps, rio 7.5 1&1/8ounce, and Remington 7.5 1290fps 1ounce. One thing i thought of is the stock retaining nut may be too tight cause I switched a shim, and i have a tendency to overtighten. Maybe it just needs more oil, or maybe the loads are too light but those are the type i always shoot and this only happened one other time 2 years ago. It happened about 4 or 5 times and i shot 60rounds. Towards the end of my hunt i would purposely empty the mag to see if it would happen. thanks in advance.