As posted above, confidence and practice are key. But as Daryl pointed out if you zero for +/-1in to beyond 100 yards with a scoped rifle, you need to be aware that at close range, say muzzle to 15 yards (i.e.when the shit has really hit the fan) your bullet strike will be below the 1 inch low you expect. That WILL make a difference if you are trying to brain something large and unfriendly! I don't have an exterior ballistics program, but at .458 Win velocity with a 500gr bullet, I don't see how you can avoid this if the +/-1in holds true to 100 yds and beyond. Perhaps only with iron sights...