Depends entirely on what you're hunting. I've been doing most my deer killing for a long time now with .30 cast bullets, 170-200 grains, and honestly can't tell a difference from jacketed stuff. Admittedly, close-ish woods ranges and nothing bigger than 200 pounds but that describes the experience of the vast majority of American hunters. I would draw the line at .22-6mm cast bullets for deer, but anything bigger, with some weight in its ass and a flat nose or hollowpoint, will do the job with aplomb- if the trigger man does his part in placing the bullet. Without good bullet placement it doesn't matter a helluva lot if you use a .30 or .45, or high vel premium jacketed bullet, you doom the animal to needless suffering.
