I've had no experience with commercial cast .30 caliber bullets, but I've cast my own for many years using a variety of designs ranging in weight from about 160 grains up to 210. My favorite is the Lyman gas checked #314299 (about 200 grains) cast of wheelweight alloy loaded to around 1650 fps.
With .308s, .30-06s, and most other .30 calibers, I've found best accuracy is almost always with a .310" or .311 bullet, but sometimes .309" will work. A "fat" nose will generally provide better accuracy than a minimal one. For best accuracy, seat bullets where they very slightly engrave, not enough to pull the bullet from the case when you extract a loaded round, just enough to make contact with the lands.
If possible from a commercial caster, buy samples of several bullets and try them. I think you'll find best accuracy with heavy bullets, but there are no firm rules with cast bullets.Get a Lyman book that has cast load data. Good luck-
