If everything else is right, you may want to look at the fletching and make sure all 3 are the same. 1 fletching glued a little different than the other 2 will make it fly off. It will corkscrew to the target. If they're all okay. You can spin your nock to next fletching (temporarily change your C- vein) and see it shoots better. I quit getting a different colored C-vein for this reason but, I do this with all new arrows to fine tune them.
I'm shooting easton flatlines 400 off my moster m6 and it shoots them perfectly.