Looks like 42.3 is your low node for accuracy. I expect you will see groups open up between 43.5 and 44.2 and then settle down again between 44.5 and 45.0.
Your low node looks to be about the duplicate of M118LR (save the difference in bullets) in terms of velocity so it should get you to 1K if you want to stop load development now. With enough scope adjustment 1 to 2 MOA difference gained by finding the "high nod" isn't going to be a dealbreaker on making the shot.
Machine guns are awesome until you have to carry one.