Another "whatever shoots best" but I started at 150 since I figured with a 300 WM you have plenty of juice, may as well get the extra speed. I have the Winchester 150 grain Power Max Bonded and they shoot really well out of my rifle. If I was starting over I'd probably try that 165 Barnes but for now I've got a stash. Also, to be clear, I've only shot 3 deer with it but I think they traveled a combined 20 yards.