It occurred to me today that free-float hand guards make BUIS worse. That is, the end of a free float hand guard, towards the muzzle end, can become canted and off center, dramatically shifting BUIS zero. Looking at my own AR with a free float hand guard, I do notice it is slightly canted towards the left, and this is causing my rear sight aperture to be maxed out to the left.
I'd either need a new barrel with a gas block front sight to fix this. I guess this means it's back to relying solely on my Aimpoint PRO red dot.
Am I gonna be KITS if I don't have BUIS? Red dots aren't the foamy diarrhea quality they were 20 years ago, but still, it's an electronic and fragile device.