My experience with light weight bullets and RBs is the faster you drive them the worse the accuracy is. Best accuracy usually come at a velocity of 800 to 1050 fps.
Also, I never found Unique to be the best powder for such loads. I suggest switching to Bullseye or Red dot. Use a starting load of 5 gr and work up testing for accuracy at 50 yards. The use of a chromograph is also helpful. The max load will be based on when accuracy goes south or you've hit 1050 fps velocity of both.