Which Citadel colour most closely approximates the default grey of the Imperial ships - in this game?

For example, the new Decimator's large grey areas.

Anyone knows?

I'm pretty sure you would have to mix some colours for the best match but other than that Vallejo Game Colour Cold Grey is fairly close which in turn is basically Codex Grey from the old Citadel line. New Citadel name would be Dawnstone but I can't say how close it is to the old Codex Grey.

I really like Tamiya primer for imperial colors. Once a thinned black wash the color is very close to factory

What did I mix up one time...it was a grayer Regal Blue that you could obviously push one way or another with more gray. I think it started simply as Ultramarines Blue and some black. I'd mix a little Codex Grey in there and see what you think. You might have to play with it a bit, but that should be a good start.