In FACTORY loads, you may be surprised at how close SOME of them will be to each other. Generally, in factory loaded ammunition, the 150's will have a bit more muzzle velocity and hit higher BUT, and here is where the SOME comes in, there are SOME factory loaded ammunition that loads the 180's over a hotter charge giving the 180gr bullet the same MV as the 150's. But as NM stated previously, case capacity becomes an issue for 180's for the .308 case.