The screw works just like I hoped it would. Overtravel is my biggest issue with a trigger. I can deal with creep, a heavy trigger, or a rough trigger, but too much overtravel makes my groups look like a shotgun pattern. I would say that just getting rid of the overtravel on my 7400 reduced my groups by 30% on average. Getting that trigger spring helped a lot too. My groups probably shrunk almost in half by doing the screw/spring. I don't think it was the gun itself with any problems, it was my ability to shoot it better with the alterations.
I just drilled and tapped the guard and got an 8x32 allen head screw from Lowe's. I think two of them in a pack cost a buck or so. I think it was an inch long?? Then I put the screw in and kept turning it in until the sear wouldn't drop, then backed it out just enough to let everything work like it should. I marked the screw, pulled it out, and cut it to length with a Dremel tool.
If you decide to do it, make sure you use enough oil on the tap, as the guard is aluminum, and you don't want to mess it up. I oiled the screw when I first put it in too, to unsure that I didn't strip it out. I also put drop of green loctite on it, just to keep it from backing out due to the vibrations of the gun.
