I have a 308 with the boss. I didn't like the boss because it was too loud for hunting, so I bought the boss CR. I played with mine quite a bit when I first got it. It was my experience that adjusting the boss moved the point of impact a surprising amount, but I could never seem to get it to shrink groups. I ended up getting frustrated with it and left it set at an arbitrary point and tailored hand loads for it, the rifle does shoot nicely. When I bought it I thought that the aesthetics of the boss would not bother me, but it does. I plan on doing some more experimenting this summer.