gutter is an improvement... normally in the sewer...
<- I just wanted to give that emoticon a run...
Jays, what are you doing?? hunting plinking? what are you shootin?
if you sight in for a reasonable Maximum point blank range, you can sight in for, depending on certain things, between generally 20 to 25 m and be sighted for your MPBR of say 230 or 250m... (not 100m). this is the result of the projectile trajectory crossing the sight plane twice..once on the way up the rainbow, at 20 odd metres... and another time on the way down the other side of the rainbow at 200+m.....
Provided you know the trajectory you'll have an idea of where it is at 100m to either adjust or to use the MPBR method to always be within you 2,3 or 4 inches at any range within....