Haven't read the whole thread, but that stuck out pretty quick.
As long as we're talking about bad advice pet peeves, when someone is having undergassed problems and the peanut gallery collectively suggests an AGB, that winds me up pretty good. AGB's don't add gas beyond the maximum you're already getting with a standard GB. Come on people, use your brains.
And maybe the nuances of subsonic gun tuning are beyond me, but for supersonic stuff, if your gun isn't running at all, a small change in buffer weight won't fix it. And if it does suddenly work, it's gonna be super borderline. But the go-to gunshop counter advice is always to go from an H2 to an H3 or whatever.
Alright, I'm done ranting.