Fred C thanks for posting the problem you discovered with Krag rifle. That takes a lot of guts and I'm glad no one was hurt!
Without having a rifle in my hands to study and try to replicate an "AD" one thing immediately pops into mind that admittedly I haven't tried with a Krag rifle.

It's a question sort of so bear with me until I can get one apart to study further.  I quickly looked at your links and without quoting I read where you had some fitting problems initially regarding your trigger.

Now the question, will a Krag trigger that is not captured inside a trigger guard release the sear when its pushed forward like a Springfield 1903?

In your image depicting the shank of the trigger and the area captured by the box right at the beginning of the curved face of the trigger. That area looks to be very slightly peened over right at a point where the guard slot would cease its forward movement.

Is it possible enough clearance is evident to let the trigger move forward. Whether it be from slack or wear through use? It was just the first thing that occurred to me.

Even if the face of the shank is not soft if the guard is not drilled or inletted to perfect alignment enough clearance could have just occurred with use to allow the trigger to be pushed very slightly forward allowing the sear to work, but in reverse. I never tried to push a Krag trigger forward but it will happen in other rifle types of similar design.

Ill wait to read any other findings. Thanks-Brian