****DISCLAIMER: polished internal mating surfaces don't kill people, bullets kill people. These mods don't lighten the pull, just smooth it out. I'm not a glock armorer. Also, don't pull the trigger until the firearm is aimed appropriately(For the manual safety guys). ***
That all said, here is My post from a previous thread: We shouldnt try to make a glock what its not. It's like when people put low profile tires and big rims on full size trucks. It makes them worse at being a truck and still a poor example of a sports car.
Now, the trigger can be greatly improved with a little polishing in a few areas....aka .25 trigger job(the same effect will eventually be felt after 6,000 rds, I'm just cheap and impatient). The largest improvement and least invasive area to polish is the face of firing pin safety and the angled surface on the trigger bar that engages the firing pin safety. (Just polishing!!! Do not remove metal or change the factory angles!!!)
I also use a fine tooth round file and put a slight concave in the trigger safety. I make sure that the trigger safety is fully depressed and file until it matches the face of the trigger. Again, just enough so that it will always fully engage and disengage, but not so much that it renders it useless.
These mods take the grit out of the trigger pull and makes it more comfortable to shoot during extended range sessions. Nevertheless, these mods void warranties and get Liberals anxiety levels up.