this all depends on your shooting style. if standing shooting then 3-1/2 to 4 would be fine. but, if off the bench, you really need to concentrate on where your face is in relation to the scope. I had a 458win mag with a leupold 1-4x. never got it in the forehead if shot standing. but I would usually end up with a bleeding forehead when I shot it from the bench. the leupold 2-7 has a very long relief (now on my 458 win mag custom) and the 6.5-20 varX-III also has a long relief (on my 300 rum sendero)