I don't know what you think that proves? Are you insinuating that no gunsmiths know this and incorporate it in their builds? are you insinuating that without the "proper .004" setback in headspace will render the firearm useless? Clearly there are people running AI in AR's. I am trying really hard not to bash you, but you have brought zero to the table and zero to defend your claim. So what exactly are you saying? I am sitting here scratching my head.
