snoman, I don't have any exact measurements to share with you, but at 25 yards my barrel could produce a tight group just using a concrete bench as a rest for my arms. And, this is with mediocre eyesight ...
I'll take it out again in a couple of weeks and redo my sighting at 50 yards on bags - I'll let you know what I find. Also, you might check out what Hans has on his site at
http://www.vangcomp.com/test_results.htm regarding pattern testing with shot.
I will tell you that after my class, and seeing what this gun will do at the range, there is no question in my mind that slugs are a tremendous round in this gun. I look forward to seeing how the groups look at 50 yards, and doing my best on bags to give the gun a fair test. While it can't be a rifle, it seems to give excellent accuracy with slugs. And, boy ... those holes are big!