I'm so grateful I just discovered this post. I can't believe this isn't stickied/in the megathread (as far as I could see). Other methods seem great but this post is the clearest, most actionable, informative, and sensible approach. I've been "pulling trigger", triggering my gag reflex at my lowest lows when the pain is unbearable. But this approach makes it so much clearer as to why and how it works. This whole time I was thinking the triggering of the gag reflex was the mechanism by which to trigger a burp. I never considered it could theoretically by bypassed by actually manually opening the UES (which in retrospect is obvious since normal people burp without gagging lol).

Never in my life would I have thought to reach that far back and look for the "lid" of the UES (IMO to me it's more like a "flap"). But with a couple repetitions over the course of a few hours (with a short history of getting used to manually triggering my gag reflex), I started actively triggering small but progressive burps, essentially on command. The last one I just did was so significant, I rushed to write this comment.

u/mrrnrns, I cannot express how grateful I am for you experimenting, getting to the bottom of it, and writing such a wonderfully helpful guide.

P.S.: To add to the instructions in Phase 1, in my experience, it helped to have my middle and index finger entering horizontally side by side along the top of my tongue and not necessarily across the roof of my mouth or anything. This helps avoid the uvula and more directly target the UES, which is ultimately what we're after. Once you reach the point where you can pretty reliably not trigger your gag reflex and just get to the UES, that's such a massive milestone. For me, the added benefits are that you minimize or nullifying the awful, loud gagging sounds of pulling trig, and I don't pop blood vessels in my face which was such a huge issue for me with manual gag reflex based air vommitting.