Thanks for all the great advice.
This nosecone is ABS, most of the ones I've worked with are PVC, ABS or PP, the PP is too soft and nothing sticks to it.
I searched the archives and heard people mention the body-filler and thought it would work just about the same as the model filler clay I had been using. But it sounds like it sands a lot easier. I will try the body filler, if it sands faster then it will be a 50% gain in time.
My process is pretty simple but lengthy: Scratch up the nose with 80grit sandpaper and apply a light coat of krylon ultra flat black (It seams to stick better then any primer I've tried) once the primer has dried it shows every imperfection, and I start sanding. Any pits, seams, cracks get a light fill of putty. Once dry I stand. Because it was a light coat I usually have to add 1-2 coats more of the putty to fill in all the cracks (the testors brand putty cracks in think layers and take a full day to dry if thick). I'll add a few layers of ultra flat to get a very smooth surface then lightly sand with 220 grit to better bond the final coats of paint. This method produced very nice results, but is very time consuming on larger surfaces.
-cat