I recall grauhanen had located a pic of Anschütz's testing tunnel. There were piles of empty RWS Target Rifle boxes, implying that was their preferred ammo for testing. In the corner of the photo, some gold boxed RWS could be spotted, it was not clear whether it was Special Match or R-50. Eley Tenex could also be seen. I would suspect that if a passing target wasn't shot with RWS Target Rifle, they would then try some of the other varieties before determining a fail. It would not be economical to use the highest grade of ammo for mass testing.
*edit* haha, there it is above, posted while I was typing. RWS Club, I see, not Target Rifle.