Rob: I'll attack this from a different angle. But first, the screw you see on your L && R triggers is the adjustment for the let-off, not for adjusting the contact of the mainspring on the rear trigger.
Now, with the triggers unset, the mainspring is in contact with the seat on the back end of the rear trigger, forcing the trigger's bar up into the air. This is the part of the trigger that fires the lock. On L & R's triggers, there is a lot of steel in the triggers that can be ground away to clear the sear bar, but sometimes, some work has to be done to the mainspring and/or the seat on the back of the rear trigger. Careful filing or grinding can be used to remove metal from the seat on the trigger so that the spring no longer presses on the trigger while it is at rest (unset). This will allow the rear trigger to rotate and 'float' with it's forward extension sitting much lower than when the spring is pressing down hard on it. In this way, it will clear the sear arm so that the lock can be cycled without setting the triggers. Another way to achieve this clearance, yet maintain a very powerful functioning mainspring, is to remove metal either from the tip of the mainspring, basically providing the same affect, or from the bottom of the spring in the area of the attaching screw. Changing that base angle very slightly can tip the spring so that it clears the seat of the trigger, again allowing the trigger to rest with it's forward extension lower in the gun, clearing the sear arm.
I think some drawings might explain this better. I'll see what I can come up with, but right now, I have to get to my build.
