Jeffm

I ran into this problem today also. Tore the rifle down, checked gas block ejector springs, donuts buffer spring all to no avail. Problem was I was zeroing a scope and had the mag resting on the shooting bench while shooting in turn craming the mag into the upper reciever. After coming home stripping the rifle it dawned on me what I had done so I went back to the range and shot it standing up with no pressure on the mag it ran like a sewing machine