Well if memory serves me right going off of what I seen of your patterns before that were right around a 150 avg at 40yds with that same gun, choke and load, I can't for the life of me going off of my years of personal patterning experience see how you could only lose 100 shot going from 40yds to 60yds. The exact same thing can be said from 40yds to 50yds and only losing 50 shot. That would be like saying if your gun shot a 250 30yd pattern you should be able to post a 200 shot pattern at 40yds. I don't know a 20GA out there than can do this with that same load regardless of the choke.