Hey, if you guys are into patterning shotguns you might want to try a product called Shotgun Insight. I have an early version of it and have used it extensively with excellent results. The procedure calls for shooting a target on a clean sheet of paper (white works best) and then taking the target indoors where the processing is done. A digital image is taken of the target and supplying some data to determine scale and aiming point. The software takes over from there, recognizing the pellet strikes and doing all the mathematical work. The output will provide you with more info than you will ever need. Their website will describe the product quite well.
www.shotguninsight.com