Thing is, the first set doesn't seem that off if you ignore the 150 potency point. Example: 1.571875 damage per potency would lead to:

200 potency 95%: 298.65625
200 potency 105%: 330.09375
320 potency 95%: 477.85
320 potency 105%: 528.15

And the 329 could be excused because of the 0.3% chance of actually getting something to land in that window.