i found this online and did it to my gun with just a spring out of a pen and a screw that i cut down to size with bolt cutters. it was easy to do with no gun modification required and reduced the trigger pull weight by at least half i'd say, i dont have a scale.
- make sure you dont lose the little c shaped ring that goes on the pin holding the trigger in, mine shot off and i almost couldnt find it!
there was some yellow crap in the hole where the screw goes in im guessing thats for warrenty anyways its gone now, use the tension pin method if you want to keep your warranty.
good luck i think you'll like your edge even more after this easy little mod!