I was one of the ones picked by BScar to test that trigger before release and it is definitely one of the biggest improvements I've made to a rifle. The prototype that he sent had perfect fit and finish and has functioned perfectly through hundreds of rounds. One thing that impressed me is the fact that it is a true 2 stage, which allows for a safe 2nd stage at a couple of ounces of pull weight. I could never get other trigger modifications to pass safety tests at anywhere close to that weight. The trigger plus the group buy barrel has turned my 455 into a hammer. I had to mill out my chassis a bit to get it to fit but any newer chassis that's inlet for the Fly trigger should work fine.