There are a couple of nutplates on each spar web at the root that are pretty much the first thing installed when you start working on the spars. On one wing all 4 of the countersinks were shallow by probably 4-5 thousandths. This is an area where the spar has to slide into and mate with the center section after you build the fuselage and the tolerance here is really tight. I was concerned about the proud rivet heads getting hung up when I eventually try to slide the wings home, or maybe fretting against the center section afterward and either causing corrosion to start there or maybe wearing a divot in the center section that would make it hard to get that wing out if anybody ever has to remove them in the future. I asked Vans builder support about this and Sterling said it would be fine, but it was really bothering me that I might struggle to slide these wings home and was also going to have this point load in an area thats held together with about a dozen close tolerant bolts, so I drilled them out. Reworked the countersinks to the proper depth with a microstop, swirled the hole with primer on a q-tip, and reinstalled the nutplates. The bolts that go into those nutplates are close tolerance and go through several layers. It seems like it's to my benefit to make sure that nut plate is dead in the center, because theres no wiggle room in the hole at all. To do that, I stacked enough washers on a bolt that I could snug it up on the nutplate without going deep enough to engage the locking portion. This made sure the nutplate was 100% centered. Was able to squeeze the rivets with a longeron yoke.