Interesting.  I have a 1916 made action that has the spring.  I looked at the Stomperud, originally an 1897 Steyr action and noticed for the first time that there's a screw where the rivet is in para's pic.   It bears on the rear of the trigger and has a range of motion of about 1/8".  Adjusting the screw down (turn right) takes out most of the first stage.  I've been playing with it some, it has a bigger range of motion than what I originally thought.  So far I have all the first stage taken out.  I guess the guys at the US Armory missed this feature!  Thank you fellows, now I have an adjustable single stage trigger.  Vertical bolt movement in the action is minimal, but I won't adjust it down enough that I don't have good sear engagement.  There might be a hint here for US Krags, least the sporterized ones.