A couple of years ago I ran across a gunsmith who had computer software that would calculate how much a rear sight had to be moved to effect bullet impact at a given distance. He would input the sight radius of the pistol, the distance (R or L) that the impact needed to be moved and the exact distance at which the group was originally shot at. I have done a lot of searching online for a software like this but can't come up with anything like it. Does anyone know of such a software? If you do know --- Name of software? Where to get software? Price?