I clecoed the F-770 skins in place to use as a template to devinyl and mask the forward ends of the F-773's where they underlap the F-770 forward side skins. After devinyling I deburred the outside of the rivet holes. After removing the forward skins, I scuffed, cleaned, and primed the forward ends of the aft skins (photo 1).
Forward ends of F-773 that underlaps the F-770 forward side skins are primed.