The "Solo Operative," Artifact Perk does not proc as it should. "While you are the only member of your fireteam, precision weapon final blows increase weapon damage until you are defeated." The damage you get at 25x-stacks is the same as the damage you get at 50x-stacks, and the same as you get at 100x-stacks, and the same as you get at 150x-stacks. Tested over and over in the Shooting Range with Vex Mythoclast. "128 dmg" on headshots, no matter how many stacks you get.