I think your group size measurements may be a little off. Just measure the widest part of the group with a caliper and then subtract one bullet diameter.
Group 2 is probably closer to 1.5" than 0.4" based on the .30 diameter of the bullets and estimation.
ETA: The largest group you show is 0.42". 0.42 + 0.308 = 0.728" The diameter of a dime is about 0.705". This means a dime should cover every group you had except group 2 should be just a hair bigger than the dime.
Also, not knocking your shooting at all. It looks good, but I think your size method is flawed somehow. Nice looking smoke pole too.
I was thinking about it today and I agree, the method that I used calculated the average radius, not the MOA accuracy.