Spencer triggerbar variant - this is what?

[Mor-Kik]

Hi all -

I recently acquired this Spencer trigger bar, and was wondering what this projection or pin IN the front screw hole is for.  I've seen the pins for limiting Stabler cutoff travel on others, but those seem to be located well away from the screw hole.  I would suspect that this might be for a different firearm, but its fit is simply perfect to buttstock and receiver.   I've attached a photo - hope it takes

Any help or thoughts very appreciated - thanks!

[Herbert]

It looks to me to be whats left of a lock screw to stop the trigger plate frame screw from coming loose,weather a original expermental or latter gunsmith fix I could not tell

[Mor-Kik]

I believe I may have found my own solution - definitely a stabler cutoff related mod.  There are so few photos of the BOTTOM of a cutoff, and that was the clue I needed.  Found a good photo and put a top/bottom view together to show how this rather ingenious setup should work.