I have had good luck at times with Wolf Match target but I usually use RWS target.
You might try sorting some of the cheaper stuff by rim thickness and see how it works.
I have tried Eley and have gotten good groups, but the cases expand around the ejector star and make it hard to eject the cases. I have a similiar probelm with my T/C and Eley. That problem requires me to remove the barrel to get the case out. Makes it kind of tough to get 5 shots off in two minutes.