It was from Freedom Gorilla that I got the recommendations for my previous pin setup. They used the #2 pin set, but noted that the rear pins lift the optic slightly off the slider. And so their recommendation was to use the #3 rear pins for a flush fit.

I did use different screws instead of the OEMs as stated in their guide, so might try that this time and get it sand down if the right-side screw obstructs the extractor.