Let me post what I think is the scenario that caused the accidental discharge. I have taken the gun apart and looked at the internals.
Like I said the gun has about 3000 rounds through it and the action is still quite "stiff". The shotgun has been setting for the last 5 years due to my illness.
When I started using it again I never properly oiled the gun. In using the top barrel only I never fully opened the action. The un-oiled hinge pin and the stiffness of the action contributed to the action not being fully opened. The "recocking" or the resetting of the hammer/sear is accomplished in the very last part of opening the action. In effect I was never fully resetting the sear. As I shot more and more the hammer finally worked it'sway off off the sear and caused the AD.
I will take a primered only round and place it in the bottom barrel for the next couple times I use the gun. That way I will know if the primer is struck off goes the gun to a smith.
