The brass plate seems to function in a manner similar to a device pictured by Dr. Hudson in his book, "Modern Rifle Shooting".

I suppose the 'two-stage' military-trigger was unfamiliar and unpleasant to a lot of shooters, during the late 1890's and early 1900's.

In that era, the initial (take-up) stage was called "drag". These devices hold back the trigger so it is at the 2nd stage.

(I grew up with two-stage triggers and like them. So this is a non-problem).

I did notice, the other day, when some Krag actions are out of the stock & trigger-guard, the trigger (when pulled) may move sideways and the sear will hang-up on the bottom of its receiver opening.
The Krag trigger-guard serves to keep the trigger mechanism centered.

Attached photos: Dr. Hudson's trigger modification and an interesting 'set-trigger' fitted to a Krag. (I don't remember where I got the 'set-trigger' photo).

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