Hey TES;
when I had to do some filling on a kit I was going to polish for a Natural Metal finish I'd use gloss White, but I've seen alot of people use Gloss Black, and one person used any gloss color they had at that time, and the NM finish was beautiful after they where done, so you could use just about any gloss under coating, it's just there to make the filler not as absorbant to the Alclad paint, and it's easier to polish a gloss surface then a rough surface
Ugly Butt Effective Hawgs
Cuda
84 of 795 1/72 Aircraft Competed for Lackland's Airman Heritage Museum
Was a Hawg Jet Fixer, now I'm a FRED Fixer
'Cuda