I have my own bushnell boresighter and use it whenever I mount a scope.I always start at 100yards and the point of impact is always on the paper usually within 4" to 6" of dead center.You must know your boresighter as many have grids that are not perfectly centered.My own unit is about six inches off at 100 yards but after using it a few times you realize this and simply allow for this error.Using the boresighter saves me time and ammunition by skipping over the 25 yard and 50 yard targets and going directly to the 100 yard target.Many people make the mistake of firing one round and then moving the scope at 100 yards.I have watched many people burn over a box of ammunition chasing the point of impact all over the target by adjusting the scope after each shot.Shoot a three shot group then adjust the scope using the average of the group.Adjust the scope and fire another three shot group and adjust if necessary.Usually the scope will be sighted in with two adjustments for a total of nine shots.