JRS is right. BC means nothing inside of say 400-500 yards on the 308. You'll never see it in drop or hardly at all on wind. Yes mine are 168 TMKs. No pressure signs and great accuracy. I tried for the most only because I considered 600 yards as a possibility on whitetails. Not that 42.0 grains couldn't accomplish the same but wanted a higher speed and less drop and a little better wind defiance.168 grain? Are you getting any pressure signs or flattened primers? That is good velocity especially from a .308 and the TMK has better BC too of .535 over the Nosler BT with BC of .490
Side note, I don't even understand why the Berger 168 VLD has a poor BC of .473