These programs go into SPECIFICS,chartscover a wide range.Some charts ask for hard or soft cam but a program uses the actuall speed that a bow produces and uses that efficiency rating to find a proper spine arrow.


Example,I have a friend that has the charts call out a 400 spine for him but he is using a very aggressive cam.My program shows heneeds to use the arrow at 65#'s but the chart says he is okat 70#'s(If memory serves).He had lots of trouble grouping at 70#'s and I tried to explain why but he didn't get it.SO,I TURNED HIS POUNDAGE DOWN and he started grouping.It was all in the spine.