It's real tough to troubleshoot certain things from a distance. This is one such case. A gunsmith would need to handle the shotgun to determine the cause. You can look to see if the forend tube assembly and it's arms are out of whack. Maybe the bolt carrier/slide is a little rough, or the right or left shell latches are out of whack. It really needs an eyeball on it to see what's happening.
Lock, Stock and Barrel gunworks
SLC, Ut
USMC 69-73
"This is my rifle, there are many like it but this one is mine. My rifle is my best friend, it is my life."
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