For quite a few years I was heavily involved with shotgun patterning and the associated statistical analysis. I used a product called Shotgun Insight. It is not quick and dirty but delivers on the analysis end. It involves shooting patterns on clean paper, taking a digital photo of the target, loading the photo into the program, and registering the photo dimensionally. All of this takes time. I used to shoot maybe 50 targets on an ideal day. Then on a slow winter day set up to do the photo work. Care on this aspect pays dividends in the final product. Then on to dimensional registration which is tedious. After all this the software does all the rest. Time consuming but rewarding.
http://www.shotgun-insight.com/intro.html