Trigger Creep

[TMan]

This has been really bugging me: I have several guns that have creepy triggers, and then there are some that have "glass break triggers".

Actually, I can understand the creepy triggers: you apply pressure and you have two metal parts that rub against each other; one moves and you feel the movement, which at times can be quite "gritty" depending upon how rough the surfaces are.

What I don't understand is the "glass-break triggers". With those, you apply pressure, you don't feel any movement and suddenly the gun goes bang. Why? What is happening? Is it that as you apply pressure that there really isn't any movement until suddenly there is enough pressure that it lets go, or are the surfaces so smooth and the amount of engagement so small that there really is movement, but you can't feel it.

Does anyone know or have any ideas/theories?

["DoubleAction"]

TMan; As you probably already know, there are some single action triggers which come from the factory with triggers that are designed primarily for target use. These triggers are made to break clean with a minimal amount of takeup, overtravel, and pressure. The most popular of these triggers on handguns are found with the 1911, which features shortened and polished hammer hooks, matched sears, and lightened hammer springs ( Mainsprings). The angle of the sear to hammer hook engagement is very fine, which also accounts for the lack of creep. The gritty movement can also be contributed to something else, other than the sear to hammer hooks. Grit can also be found in the trigger stirrup as it rides on the inside of the frame.
I once had a gritty trigger on a Sig P-226's takeup and tracked it down to the trigger bar, as it rode on the inside edge of the slide. While polishing everything else and reducing the hammer spring pressure, I reduced the trigger pull by 3/4 pound on the single action break.
While most refer to a good single action trigger as breaking like glass, some double action triggers are described as being smooth as butter because of their long strokes.
I usually check for grit and smoothness as I reassemble a pistol frame after cleaning it.