I am assuming you have a T/C Hawken which has a 1:48 twist. Not sure what twist rate is in a CVA or Traditions.
You may want to consider the Barnes 295 gr MZ bullet or go online and do a search for Leigh bullets if you really want to go with a non-toxic bullet. But if you're only looking to go to a saboted jacketed bullet you can try the 300 gr XTP bullets in either .429 or .451" with the appropriate sabot. These normally give me excellent accuracy.