I have a no brand (literally completely unmarked) flip up BUIS that I'm
still trying to figure out and get zeroed. Can anyone tell me what the A2 rear sight aperture's height is-or more specifically, the height of an A2-type carry handle rear sight-from turned all the way down? The only way I could accurately measure this would be from the underside of the sight, as I have no way to find and reference any other datum.
The aperture in this BUIS is adjusted with a screw through it. To adjust it, the screw must be loosened, the piece with the aperture moved, and then the screw tightened again. It's obviously a PITA-no wonder the thing was cheap.
So anyway, to get somewhere near zero I need to adjust this thing by measuring where the aperture
should be and moving it there.
Here's a picture of it: