At ranges less than 25 yards, the biggest factor will by your sight height, how high the sights are above the bore. It's like the viewfinder lens of a twin lens camera, the viewfinder can not see exactly the picture that the camera lens sees. So, if you are aiming at the head of a squirrel that's only five feet away, and you forget that the scope is 1.5 inches above the barrel, you will shoot under the squirrel's head, because the barrel is 1.5 inches below the scope you are aiming through.