I didn't buy my QD from DF, but the nut was slightly larger than the opening in mine also. The interference was very minimal. I made sure the wires were out of the way then installed the black flange and torqued it down, then installed the QD and slowly tightened the retaining bolts in a similar fashion to torquing lug nuts until the gap was gone. Didn't take much force and was still able to remove the QD from the flange. Interference was maybe 1 mm or less at the corners of the nut.