I would go back and load three each at least, preferably five each at 45.9 gr, 46.2 gr, 46.5 gr, and 46.8 gr. And I would be loading any relatively slow ball power with CCI 250 primers.

This will confirm if you are seeing actual decline in velocity with increased powder charge, or if you graph is simply the result of velocity variation at charge weight.

I have seen many bullet powder combinations which give 100+fps velocity spread with identical charge weights. Such large variations are more common in magnum capacity cases, but not unheard of in the 308 class.

Such variation will quickly rule out a powder for use in a particular bullet/barrel combination. But during load workup, it will produce some very quirky graphs.

Look at what these guys have to say: https://www.longrangehunting.com/threads/ramshot-big-game-7mm-08.216196/

People who choose to brew up their own storms bitch loudest about the rain.