Many standard rifle scopes have 1/4 MOA adjustment knobs while some target scopes offer 1/8 MOA (Minute Of Angle which equates to 1/4" for th 1/4MOA adjustment at 100 yards, 1/2" at 200 yards, 3/4" at 300 yards and so on.) In your case, as Arto mentioned, would be roughly 1/3 of an inch at 100...