I'm not sure about the size on a colt, but I can tell you what it does. It is actually a trigger over-travel stop. You set it so that the trigger moves very little rearward AFTER the sear breaks clear of the hammer. It makes for a shorter overall trigger pull.
As far as I can tell, typically, CW rotation of the allen screw decreases the pull length.
Really interesting....Don't ya think??
I believe it is a std. size (I don't know the measurement).
This is the over-travel screw. If you are not sure why you are adjusting it - don't!!!
The over-travel screw prevents the trigger from travelling too far back once the hammer has dropped. If you don't know how to adjust it, you could end up with improper trigger/disconnector reset, or worse - you could possibly go full-auto
Chill SB - no one's an expert here. Our advice was only meant to alert you to the fact that there are repercussions from an improperly tuned screw. Your own first post lead us to believe that you were unsure of the screw's function.
We all had to learn somewhere. This place is a great start. No one is trying to treat anyone like an idiot, and if I did - sincere apologies.
Perhaps you could have asked in your original post how to get rid of the "slop in the beginning of the trigger pull" ? At least then we would have known what your intentions were. Soooooooooo....to answer this question - no, the screw will not adjust the "slop" or take-up out of your trigger.
Sorry if you took offense to my reply. While I can't speak for Shane, I didn't mean to say in any way you were an idiot. You posted a question, and I responded with as much as I knew. Knowing Shane from in here, I don't imagine he meant any offence either.