Here's a good version to get you deeper into the rabbit hole.....The 6-ARC is basically a necked down
6.5 Grendel. This now make's it close to the 6PPC. The 6PPC has ruled the world in it's class for decades.
It's money making load mainly uses Vhitavouri 133 powder, and a 68gr bullet. Most use Bart's boat tail
avenger bullet jammed.......What Velocities are you at now ?? I will say to try a box of the 70gr HPBT SMK's
And stay between 65 and 75gr bullets......Are you running these from a magazine ??