Look at page 40 in this document on their powder cores:
The wire diameters and areas are way off from what you'd calculate using the AWG formula:
d = 0.005*92^((36-AWG)/39) [in]
I thought maybe they were insulated diameters, from their use of the term "heavy build".
But if that was the case, then the areas would still be right according to the AWG formula. But they are too large as well.
For instance 22ga wire should be:
d = 0.02535 in = 0.6438 mm A = 642.4 circ mils = 0.3255 mm^2
But Magnetics lists:
d = 0.701 mm A = 810 circ mils = 0.411 mm^2
Notice, their area doesn't match the diameter, which would lead to 0.386 mm^2.
What are they doing?
Interestingly, their current capacities are close to, but still a bit in error from the values one would calculate based on the correct areas (the copper, not the insulated wire).