Two comments on this. First, Alex is absolutely correct on this. Accuracy is a value entirely representing how well the weapon can put its bullets to where it is aimed, and thus should never be intermingled with snapshot/aiming performance (aperture size). Therefore Wil, I think that sight length is actually not at all a factor on accuracy.

In fact, possibly the best simulation of the effects of sight-length would be an Aiming Modifier: Does not affect snap-shooting, but does affect aiming.