Weatherby loads a 450 grain Barnes X, and conventional bullets up to 500 grains for their 460 Wby. I think that 1 in 16" is borderline for a conventional 600 grain bullet. Keep in mind, however, that the Barnes bullets, since they are all copper, and thus lighter, mean that they are longer than conventional bullets. As such, I really don't think that 1 in 16" would be enough.
BTW, why are you considering a 600 grain bullet anyway?
Zachary