Originally Posted by caged

i would use an 80 grit sanding disc on a grinder, take it down to bare metal then use glazing putty and sand smooth. prime and paint, then sand and cover with rubberized undercoating or bedliner of choice. when the edges get dull from sanding, i use a pair of tin snips and just cut the dull, shiny edge off sort of in an octagon shape. don't hold the disc flat, use the edge. you have to remove all the rust or it will just bubble again later.