I have the Timney trigger Drop In System in my AR pistol...It is sweet. It is set at 2 pounds 8 ounces, and it is sweet....
I didn't pay for it...the guy put it into the pistol before I got it...they are kind of pricey....
I think Cheaper Than Dirt has them for about $200.00...but they are just a drop in system...
I had problems with the first 2 RR triggers I bought, but they replaced them for free, and both have been working fine since 2002. One has about 9000 rounds, and the other 6000 rounds through it.