The flat situated at around 1 o'clock is designed to provide a stable surface for a finger to get behind while pulling the take down pin, once the pin has been pushed in all the way from the left. The location of the fingers while pinching the pin head to pull it out can differ, we put the flat in the most often used position, but if your fingers don't land on or close to it, there's still the knurling for the rest of the circumference to provide positive purchase on the pin head :)
aguila326, the flat isn't for the finger nail to go under to open a wedget, but you're using it correctly all the same. The pins are 0.030" longer so that when the pin is pushed in from the left side (with the muzzle pointing away from the user), there's more on the right side to pull from. If your finger happens to be using the flat, it's great. If not (and I've found my fingers pinching in other areas), the knurling helps, so there is no wrong way to use it.

