It takes a ton of velocity to overcome twist rate issues. Unless it's borderline at the bottom end of the powder charge it's generally a waste of powder to try pushing fast enough to stabilize an unstable bullet.
rp - was concerned about Hornady 68gr HPBTs, it was noted that Sierra 69gr MatchKings would work - listing the barrel length of his rifle would tell me whether he could step up to the Barnes 70gr TSX bullets - one the most beneficial SD and hunting use bullets currently on the market for AR15 use. It was why I noted the missing information.