SR9 Assembly issue

Hi, first post. I have an SR9 and I cerakoted the pistol flat dark earth. While reassembling it the barrel doesn't want to go all the back up and seat high enough to allow the slide to pass the cam block when trying to reattach the slide. This is about the 10th pistol I have done so the coating "shouldn't" be too thick. I'm wondering if Ruger made the tolerances so tight that having .5-1.0mil coating is not allowing the clearance. I sure don't want to have to sandblast the coating back off the slide just to see if that might be the problem but it sure looks like I might have to.
Has anyone else had an issue like this?

The cam block is seated correctly as all the pins are installed in it.