AC, I wrote a spreadsheet to do OCW analysis but it requires extensive measuring of the targets. Plus, I tried writing instructions so someone not fluent in Excel coud do it but that ended up being pretty hopelessly long and complex.
Anyway, how many targets are you analyzing? Did the targets already have a grid printed on them? How close to perfectly horizontal were the grids when you hung the targets? And what range did you shoot them at (which is another way of asking if your groups are tight or all spread out)?
BTW, I saw your post at
that other forum.

Don't you hate it when a bunch of knuckleheads clutter up your post, only to tell you you've asked the wrong question?