Ive always opted for heavier bullets in the rifles I shoot. I figure that Ive shot more animals inside 50 yards than I have over 100 and I want a bullet that will hold up on a close shot. Plus looking at the ballistics theres not really a whole lot of difference between the two IMHO.
Ive found lighter bullets expand better and transfer more energy inside the animal causing a larger wound channel. Ive never loaded 165s just 150s and 180s ,they both exited everything I shot but the 150 seemed to put the deer down quicker while the 180 seem to zipp right through w/ less tissue damage.
lighter bullets also have less recoil allowing me to shoot tighter groups and have better shot placement on game. for deer & black bears Id go w/ 150s for hogs and bigger stuff 165s.
For loooooooooong shots mabye the 165 as well due to the higher BC and less drop(.387 vs .338)