I have never owned one but a friend of mine does in 300win.mag. The arguement is that if you handload you dont need it. My buddy does reload and had a reload perfected. ready to hunt right. Wrong!!! his ammo got left behind when he loaded up (@300 miles). The boss allowed him to drive to the nearest town buy 4 boxes of premium ammo and proceed to sight in then tune his gun to the new load. I was impressed. it also allows you to tune a rifle to a bullet you preferr that your rifle doesnt like (barnes-X comes to mind although I've never had any problems w/ them).