If this A.D. has not been easily understood or reproducible, there are a few areas of concern that could alter normal function of the entire trigger mechanism. I guess anything affecting normal flow of motion from one part to another could cause improper action such as an accidental discharge.

After cocking, the trigger is pressed to the rear. The slack is taken up in the first press of the trigger rearward until the second stage is reached where the sear is engaged to be released from the ledge of the firing pin rod. There is pivot at the "hinge" of the trigger to cause this sear release with response from the trigger spring pushing rearward at the front of where the sear attaches to the receiver. The rear most part of the trigger must be clear to allow for it to move upward to allow for the hinge to pivot and release the sear at the point of contact with the firing pin rod to allow the spring release of the striker in the bolt to hit the bullet primer.

So, if anything affects any part of these actions, something abnormal and potentially unexpected can happen. That could include any debris temporarily in the way of the sear spring, pressure laterally on any part of the sear or trigger to prevent smooth movement, debris in the way of the rear part of the trigger that would prevent pivot of the sear and trigger at the hinge, metal burrs or rust preventing smooth and predictable motion of any of these parts or mechanism.

I also could see where there could be "premature release" of the sear from the firing pin rod ledge if either of these is not squared off and improperly ground or worn down and not permitting solid engagement.

It would be nice to see pictures, Fred, of the trigger and sear to see if anything is worn abnormally. The trigger spring could easily be replaced, as Butlers recommended, and make sure the trigger seat is clear front and back.

This solves nothing but just serves as an additional attempt to evaluate the situation.

Thanks again Fred.