I tend to agree with Zelda on this on flyboy. I believe some people go a little overboard with the "pinkness" of their red oxide primer. That pick of yours is one example. Here is a pic of conserved red oxide:
In some cases I might favor a lighter shade of the red oxide, adding a little white to the mix, if it were for example, tank still on the assembly line that has seen no exposure other than the dust in the air of the factory. But, a vehicle like Zelda's that has had an application of zimmerit over it that has broken off, and has subsequently been rained on and walked over and mudded on, etc, it is bound to be darker than that factory fresh shade.
I myself use Vallejo red oxide primer comes out darker than one would expect looking at the bottle, but that is true of a lot of acrylics. My stug that I did a while back featured one red oxide schurzen piece, and it turned out pretty dark too. It doesn't help that the picture sucked...
Anyway, just my two cents.
-Kevin