Wiggle doesn't mean inaccuracy
It certainly does, as anyone who has used tensioning pins and shot ar's at long range competitively will tell you.
It provides a consistent recoil path for the rifle and consistent harmonics to have a tight upper and lower.
I grant that you certainly wouldn't notice if you were just running factory ammo and/or shooting shorter ranges in a somewhat non critical setting.
Being a piston gun, who knows if the acr is even accurate enough to tell.
I'm sending mine to Herron for a bartlein barrel, and will do what I can with epoxy to tighten the fitment up when it gets back.