Quoted Text
Yes I do believe all exterior metal was primed with red oxide at all points in the war.
Some vehicles, such as the Panther and Jagdpanther, had an anticorrosion treatment that was a 'cold' (i.e., slightly bluish) grey color; there is some evidence in color photographs of the Daimler-Benz and MNH plants from the end of the war that this was not always oversprayed in Rotbraun primer. Additionally, peripheral subassemblies, like storage boxes and mudguards, that came from other suppliers may not have been in Rotbraun primer, and there are examples of gun barrels with just the gray heat-resistant primer from near the end of the war. But these are all special-case exceptions to the standard.
Overall Rotbraun primer was the standard; it would be difficult if not impossible to be
provably wrong if you are not modeling a specific vehicle with color photographic evidence to the contrary.