When I painted my HD 2000 Ultra Classic (in projects section) I used Evercoat Poly Flex Filler: http://www.evercoat.com/product-detail/ ... 100411/us/

Didn't have round holes to fill though, just some cracks and gouges to repair. Painted black and cut and buffed. No issues whatsoever.

I couldn't find anywhere on them what they were made out of but guessed it was SMC.

'68 Coronet R/T wrote:When I painted my HD 2000 Ultra Classic (in projects section) I used Evercoat Poly Flex Filler: http://www.evercoat.com/product-detail/ ... 100411/us/

Didn't have round holes to fill though, just some cracks and gouges to repair. Painted black and cut and buffed. No issues whatsoever.

I couldn't find anywhere on them what they were made out of but guessed it was SMC.

Funny enough that is the Exact product that I used...

sounds like its just shrunk ahere the holes were, a good fibreglass filler to help stop any movement within the hole, then i would have feathered the normal filler out over the repair by a fair amount, this will help avoid shrinkage, then a good epoxy to seal it up, then a blocking primer.
remember that filler can take days to fully harden in certain climates, and i have had stuff shrink a few months after the car was painted!!
if you relied on your primer to fill more than its designed for it will shrink back, solvents can take weeks, months or even yrs to fully evapourate out of some lacquers,
a long way around a shortcut is to use a spray polyester over the whole panel, basically covering the whole panel with filler, then the whole panel becomes part of the repair, it cant all shrink, thats why you see whole panels covered with filler, it helps avoid shrinkage (aswell as making the whole panel of the same sanding substrate, makes it easier to get flat and feater out!!)
just a few ideas, and the way i do things, they work well for me, maybe not every1's preffered methods tho
krem