Tpcollins,
You have it backwards. Greater length gives air pressure a longer lever arm with which to try to turn the bullet and make it tumble. For a given rifling twist rate, length is the single most influential factor on bullet stability. Weight comes second, and is only able to predict stability among bullets of similar construction because it then tends to predict length for a given weight. Muzzle velocity is the least significant influence.
Bottom line, whether or not you can get that Barnes to stabilize will depend mainly on your rifling twist rate, and to a lower extent on your muzzle velocity. There is a stability estimating calculator on
this site if you scroll down to the bottom of the page.