This is not because your rifle doesn't like RWS R50 and prefers RWS Target Rifle. It will "like" R50 just fine if you get a different lot. Equally, there will be lots of Target Rifle that do very poorly in your rifle. Performance varies by lot. You've got the wrong lot of R50.In my Walther there is a very noticeable drop in accuracy from RWS 50 to RWS Target Rifle. Same with my Savage Anschutz.
As R50 is their top of the line ammo (and at least 2 levels above Target), I would certainly expect - yet not guarantee - that result.What I mean is my Walther and SA both shoot RWS 50 much more accurately than RWS Target Rifle. Sorry that was not clearer.