It is nearly impossible to predict what ammo your particular rifle will "like". If the V-max's are working well, stick to them. Experiment. That is the only way to know for sure. With a 1/12 barrel, you will likely find 55gr to be the heaviest bullet that will shoot well. V-max is a very good choice anyway.
In life, strive to take the high road....It offers a better field of fire.
"Robo is right" Fuzzball