Lefty,
Just at or near max you are usually hitting an accuracy node. There are also accuracy nodes further down from max for the 168gr and 175gr bullets. The traditional way to find them is to do a complete ladder test. However, you might investigate the new OBT (optimal barrel time) method of calculation if you have Quickload. Other than that you have to become a seagull and beg for the info from those who have done ladder tests.

For example, with Varget and the 175gr bullet, there is an accuracy node at max of 44.9/45.0gr. You'll find an accuracy node lower at 43.5/43.6gr which is commonly used by most shooters, and one lower at 42.2gr. Of course the H2O capacity of your brass matters (Winchester has more capacity than Federal for instance in 308).