Im having some issues with my priming process on my cab, doors and front end sheet metal parts. My cab was blasted with walnut shells and the fenders with copper slag. Etching primer was then sprayed over the bare metal, filler work was done after scuffing the etch primer, then re-etch primed over filler and spots that were sanded to bare metal from sanding the filler. I then sprayed 3 coats of 2k high build urethane primer but it did not fill the scratches and pits left from the copper slag. My body man told me it would fill them but i should have sanded the parts first so they were smooth before priming. wondering if i should wet sand or scuff the urethane primer with 400 then spray epoxy primer over to fill the scratches and pits? maybe this is a no-no. looking for some opinions of what my best option would be. Might just have to sand everything off and start over?