I find what shoots best and stick with that (usually). The 168 gr hornady shoots best in both 30-06's and both .308's ...... so that's what I use. I found something interesting: I have a bullet drop type scope and it tells me that a 168 gr bullets needs 2600 fps to match the drop indicator. Guess what. That is just what shoots best in all four rifles. Guess they know what they are doing.