guess i would take in to consideration the distance that i will be shooting most of the time. if most of my shots are going to be at 50yds, then site in dead on at fifty! but learn your gun and shoot a bunch at 25, 75 and a 100, even 150yds, always aiming at the bullseye so that you can see how high or low you need to aim to hit the target at what ever distance that it happens to be at!
enjoy!!!