I'm trying to determine what actual shade it is- there are more than 50 shades of gray!
I'm trying to start my Schneider kit, and presumably suspensions will be gray while camouflage will be placed on the upper areas (I assume that from pictures I saw). Also, is this a standard gray color for any machinery, such as tanks from different nations?
France started the war with everything; vehicles, guns and locomotives painted "bleu artillerie". I believe it to be your base colour. There was an appropriate Humbrol mix given here on the Landships site some years ago.