I have the exact same rifle, and had very similar problems with that bullet weight. the best load i came up with was 88.5gr reloader 25 pushing a 225 grain interbond. i consistantly get very tight groups (for a factory barrel). the issue is low B.C with the 225gr. the best bullet for in th 250gr range was the Sierra game king with my gun. i was getting 1" groups at 100 yards with those (though i never really tried to develope a really good load, makes me wonder
). if that doesnt work i would rebarrel to somthing a BIT heavier and go to the edge or lapua.